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  • Lots of first chance Microsoft.CSharp.RuntimeBinderExceptions thrown when dealing with dynamics

    - by Orion Edwards
    I've got a standard 'dynamic dictionary' type class in C# - class Bucket : DynamicObject { readonly Dictionary<string, object> m_dict = new Dictionary<string, object>(); public override bool TrySetMember(SetMemberBinder binder, object value) { m_dict[binder.Name] = value; return true; } public override bool TryGetMember(GetMemberBinder binder, out object result) { return m_dict.TryGetValue(binder.Name, out result); } } Now I call it, as follows: static void Main(string[] args) { dynamic d = new Bucket(); d.Name = "Orion"; // 2 RuntimeBinderExceptions Console.WriteLine(d.Name); // 2 RuntimeBinderExceptions } The app does what you'd expect it to, but the debug output looks like this: A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll 'ScratchConsoleApplication.vshost.exe' (Managed (v4.0.30319)): Loaded 'Anonymously Hosted DynamicMethods Assembly' A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll A first chance exception of type 'Microsoft.CSharp.RuntimeBinder.RuntimeBinderException' occurred in Microsoft.CSharp.dll Any attempt to access a dynamic member seems to output a RuntimeBinderException to the debug logs. While I'm aware that first-chance exceptions are not a problem in and of themselves, this does cause some problems for me: I often have the debugger set to "break on exceptions", as I'm writing WPF apps, and otherwise all exceptions end up getting converted to a DispatcherUnhandledException, and all the actual information you want is lost. WPF sucks like that. As soon as I hit any code that's using dynamic, the debug output log becomes fairly useless. All the useful trace lines that I care about get hidden amongst all the useless RuntimeBinderExceptions Is there any way I can turn this off, or is the RuntimeBinder unfortunately just built like that? Thanks, Orion

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  • data source does not support server-side data paging uisng asp.net Csharp

    - by Aamir Hasan
    Yesterday some one mail me and ask about data source does not support server side data paging.So i write the the solution here please if you have got this problem read this article and see the example code this will help you a Lot.The only change you have to do is in the DataBind().Here you have used the SqlDataReader to read data retrieved from the database, but SqlDataReader is forward only. You can not traverse back and forth on it.So the solution for this is using DataAdapter and DataSet.So your function may change some what like this private void DataBind(){//for grid viewSqlCommand cmdO;string SQL = "select * from TABLE ";conn.Open();cmdO = new SqlCommand(SQL, conn);SqlDataAdapter da = new SqlDataAdapter(cmdO);DataSet ds = new DataSet();da.Fill(ds);GridView1.Visible = true;GridView1.DataSource = ds;GridView1.DataBind();ds.Dispose();da.Dispose();conn.Close();} This surely works. The reset of your code is fine. Enjoy coding.

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  • Shuffle tiles position in the beginning of the game XNA Csharp

    - by GalneGunnar
    Im trying to create a puzzlegame where you move tiles to certain positions to make a whole image. I need help with randomizing the tiles startposition so that they don't create the whole image at the beginning. There is also something wrong with my offset, that's why it's set to (0,0). I know my code is not good, but Im just starting to learn :] Thanks in advance My Game1 class: { public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D PictureTexture; Texture2D FrameTexture; // Offset för bildgraff Vector2 Offset = new Vector2(0,0); //skapar en array som ska hålla delar av den stora bilden Square[,] squareArray = new Square[4, 4]; // Random randomeraBilder = new Random(); //Width och Height för bilden int pictureHeight = 95; int pictureWidth = 144; Random randomera = new Random(); int index = 0; MouseState oldMouseState; int WindowHeight; int WindowWidth; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; //scalar Window till 800x 600y graphics.PreferredBackBufferWidth = 800; graphics.PreferredBackBufferHeight = 600; graphics.ApplyChanges(); } protected override void Initialize() { IsMouseVisible = true; base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); PictureTexture = Content.Load<Texture2D>(@"Images/bildgraff"); FrameTexture = Content.Load<Texture2D>(@"Images/framer"); //Laddar in varje liten bild av den stora bilden i en array for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { Vector2 position = new Vector2(x * pictureWidth, y * pictureHeight); position = position + Offset; Rectangle square = new Rectangle(x * pictureWidth, y * pictureHeight, pictureWidth, pictureHeight); Square frame = new Square(position, PictureTexture, square, Offset, index); squareArray[x, y] = frame; index++; } } } protected override void UnloadContent() { } protected override void Update(GameTime gameTime) { if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); MouseState ms = Mouse.GetState(); if (oldMouseState.LeftButton == ButtonState.Pressed && ms.LeftButton == ButtonState.Released) { // ta reda på vilken position vi har tryckt på int col = ms.X / pictureWidth; int row = ms.Y / pictureHeight; for (int x = 0; x < squareArray.GetLength(0); x++) { for (int y = 0; y < squareArray.GetLength(1); y++) { // kollar om rutan är tom och så att indexet inte går utanför för "col" och "row" if (squareArray[x, y].index == 0 && col >= 0 && row >= 0 && col <= 3 && row <= 3) { if (squareArray[x, y].index == 0 * col) { //kollar om rutan brevid mouseclick är tom if (col > 0 && squareArray[col - 1, row].index == 0 || row > 0 && squareArray[col, row - 1].index == 0 || col < 3 && squareArray[col + 1, row].index == 0 || row < 3 && squareArray[col, row + 1].index == 0) { Square sqaure = squareArray[col, row]; Square hal = squareArray[x, y]; squareArray[x, y] = sqaure; squareArray[col, row] = hal; for (int i = 0; i < 4; i++) { for (int j = 0; j < 4; j++) { Vector2 goalPosition = new Vector2(x * pictureWidth, y * pictureHeight); squareArray[x, y].Swap(goalPosition); } } } } } } } } //if (oldMouseState.RightButton == ButtonState.Pressed && ms.RightButton == ButtonState.Released) //{ // for (int x = 0; x < 4; x++) // { // for (int y = 0; y < 4; y++) // { // } // } //} oldMouseState = ms; base.Update(gameTime); } protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); WindowHeight = Window.ClientBounds.Height; WindowWidth = Window.ClientBounds.Width; Rectangle screenPosition = new Rectangle(0,0, WindowWidth, WindowHeight); spriteBatch.Begin(); spriteBatch.Draw(FrameTexture, screenPosition, Color.White); //Ritar ut alla brickorna förutom den som har index 0 for (int x = 0; x < 4; x++) { for (int y = 0; y < 4; y++) { if (squareArray[x, y].index != 0) { squareArray[x, y].Draw(spriteBatch); } } } spriteBatch.End(); base.Draw(gameTime); } } } My square class: class Square { public Vector2 position; public Texture2D grafTexture; public Rectangle square; public Vector2 offset; public int index; public Square(Vector2 position, Texture2D grafTexture, Rectangle square, Vector2 offset, int index) { this.position = position; this.grafTexture = grafTexture; this.square = square; this.offset = offset; this.index = index; } public void Draw(SpriteBatch spritebatch) { spritebatch.Draw(grafTexture, position, square, Color.White); } public void RandomPosition() { } public void Swap(Vector2 Goal ) { if (Goal.X > position.X) { position.X = position.X + 144; } else if (Goal.X < position.X) { position.X = position.X - 144; } else if (Goal.Y < position.Y) { position.Y = position.Y - 95; } else if (Goal.Y > position.Y) { position.Y = position.Y + 95; } } } }

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  • Mastering CSharp.

    - by Subrat
    Hi All, Want to master CSharp. Know the basics though. Please name a few very good book to choose from. I have always loved the complete reference books. Is the one for CSharp is good? Thanks.

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  • Finding a Relative Path in .NET

    - by Rick Strahl
    Here’s a nice and simple path utility that I’ve needed in a number of applications: I need to find a relative path based on a base path. So if I’m working in a folder called c:\temp\templates\ and I want to find a relative path for c:\temp\templates\subdir\test.txt I want to receive back subdir\test.txt. Or if I pass c:\ I want to get back ..\..\ – in other words always return a non-hardcoded path based on some other known directory. I’ve had a routine in my library that does this via some lengthy string parsing routines, but ran into some Uri processing today that made me realize that this code could be greatly simplified by using the System.Uri class instead. Here’s the simple static method: /// <summary> /// Returns a relative path string from a full path based on a base path /// provided. /// </summary> /// <param name="fullPath">The path to convert. Can be either a file or a directory</param> /// <param name="basePath">The base path on which relative processing is based. Should be a directory.</param> /// <returns> /// String of the relative path. /// /// Examples of returned values: /// test.txt, ..\test.txt, ..\..\..\test.txt, ., .., subdir\test.txt /// </returns> public static string GetRelativePath(string fullPath, string basePath ) { // ForceBasePath to a path if (!basePath.EndsWith("\\")) basePath += "\\"; Uri baseUri = new Uri(basePath); Uri fullUri = new Uri(fullPath); Uri relativeUri = baseUri.MakeRelativeUri(fullUri); // Uri's use forward slashes so convert back to backward slashes return relativeUri.ToString().Replace("/", "\\"); } You can then call it like this: string relPath = FileUtils.GetRelativePath("c:\temp\templates","c:\temp\templates\subdir\test.txt") It’s not exactly rocket science but it’s useful in many scenarios where you’re working with files based on an application base directory. Right now I’m working on a templating solution (using the Razor Engine) where templates live in a base directory and are supplied as relative paths to that base directory. Resolving these relative paths both ways is important in order to properly check for existance of files and their change status in this case. Not the kind of thing you use every day, but useful to remember.© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  

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  • A Small Utility to Delete Files recursively by Date

    - by Rick Strahl
    It's funny, but for me the following seems to be a recurring theme: Every few months or years I end up with a host of files on my server that need pruning selectively and often under program control. Today I realized that my SQL Server logs on my server were really piling up and nearly ran my backup drive out of drive space. So occasionally I need to check on that server drive and clean out files. Now with a bit of work this can be done with PowerShell or even a complicated DOS batch file, but heck, to me it's always easier to just create a small Console application that handles this sort of thing with a full command line parser and a few extra options, plus in the end I end up with code that I can actually modify and add features to as is invariably the case. No more searching for a script each time :-) So for my typical copy needs the requirements are: Need to recursively delete files Need to be able to specify a filespec (ie. *.bak) Be able to specify a cut off date before which to delete files And it'd be nice to have an option to send files to the Recycle bin just in case for operator error :-)(and yes that came in handy as I blew away my entire database backup folder by accident - oops!) The end result is a small Console file copy utility that I popped up on Github: https://github.com/RickStrahl/DeleteFiles The source code is up there along with the binary file you can just run. Creating DeleteFiles It's pretty easy to create a simple utility like DeleteFiles of course, so I'm not going to spend any talking about how it works. You can check it out in the repository or download and compile it. The nice thing about using a full programming language like C over something like PowerShell or batch file is that you can make short work of the recursive tree walking that's required to make this work. There's very little code, but there's also a very small, self-contained command line parser in there that might be useful that can be plugged into any project - I've been using it quite a bit for just about any Console application I've been building. If you're like me and don't have the patience or the persistence (that funky syntax requires some 'sticking with it' that I simply can't get over) to get into Powershell coding, having an executable file that I can just copy around or keep in my Utility directory is the only way I'll ever get to reuse this functionality without going on a wild search each time :-) Anyway, hope some of you might find this useful. © Rick Strahl, West Wind Technologies, 2005-2012Posted in Windows  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Amazon Product Advertising API SOAP Namespace Changes

    - by Rick Strahl
    About two months ago (twowards the end of February 2012 I think) Amazon decided to change the namespace of the Product Advertising API. The error that would come up was: <ItemSearchResponse > was not expected. If you've used the Amazon Product Advertising API you probably know that Amazon has made it a habit to break the services every few years or so and I guess last month was about the time for another one. Basically the service namespace of the document has been changed and responses from the service just failed outright even though the rest of the schema looks fine. Now I looked around for a while trying to find a recent update to the Product Advertising API - something semi-official looking but everything is dated around 2009. Really??? And it's not just .NET - the newest thing on the sample/APIs is dated early 2011 and a handful of 2010 samples. There are newer full APIs for the 'cloud' offerings, but the Product Advertising API apparently isn't part of that. After searching for quite a bit trying to trace this down myself and trying some of the newer samples (which also failed) I found an obscure forum post that describes the solution of getting past the namespace issue. FWIW, I've been using an old version of the Product Advertising API using the old Microsoft WSE3 services (pre-WCF), which provides some of the WS* security features required by the Amazon service. The fix for this code is to explicitly override the namespace declaration on each of the imported service method signatures. The old service namespace (at least on my build) was: http://webservices.amazon.com/AWSECommerceService/2009-03-31 and it should be changed to: http://webservices.amazon.com/AWSECommerceService/2011-08-01 Change it on the class header:[Microsoft.Web.Services3.Messaging.SoapService("http://webservices.amazon.com/AWSECommerceService/2011-08-01")] [System.Xml.Serialization.XmlIncludeAttribute(typeof(Property[]))] [System.Xml.Serialization.XmlIncludeAttribute(typeof(BrowseNode[]))] [System.Xml.Serialization.XmlIncludeAttribute(typeof(TransactionItem[]))] public partial class AWSECommerceService : Microsoft.Web.Services3.Messaging.SoapClient { and on all method signatures:[Microsoft.Web.Services3.Messaging.SoapMethodAttribute("http://soap.amazon.com/ItemSearch")] [return: System.Xml.Serialization.XmlElementAttribute("ItemSearchResponse", Namespace="http://webservices.amazon.com/AWSECommerceService/2011-08-01")] public ItemSearchResponse ItemSearch(ItemSearch ItemSearch1) { Microsoft.Web.Services3.SoapEnvelope results = base.SendRequestResponse("ItemSearch", ItemSearch1); return ((ItemSearchResponse)(results.GetBodyObject(typeof(ItemSearchResponse), this.SoapServiceAttribute.TargetNamespace))); } It's easy to do with a Search and Replace on the above strings. Amazon Services <rant> FWIW, I've not been impressed by Amazon's service offerings. While the services work well, their documentation and tool support is absolutely horrendous. I was recently working with a customer on an old AWS application and their old API had been completely removed with a new API that wasn't even a close match. One old API call resulted in requiring three different APIs to perform the same functionality. We had to re-write the entire piece from scratch essentially. The documentation was downright wrong, and incomplete and so scattered it was next to impossible to follow. The examples weren't examples at all - they're mockups of real service calls with fake data that didn't even provide everything that was required to make same service calls work. Additionally there appears to be just about no public support from Amazon, only peer support which is sparse at best - and getting a hold of somebody at Amazon, even for pay seems to be mythical task. It's a terrible business model they have going. I can't see why anybody would put themselves through this sort of customer and development experience. Sad really, but an experience we see more and more these days. Nobody puts in the time to document anything anymore, leaving it to devs to figure this stuff out over and over again… </rant>© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  Web Services   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • HttpWebRequest and Ignoring SSL Certificate Errors

    - by Rick Strahl
    Man I can't believe this. I'm still mucking around with OFX servers and it drives me absolutely crazy how some these servers are just so unbelievably misconfigured. I've recently hit three different 3 major brokerages which fail HTTP validation with bad or corrupt certificates at least according to the .NET WebRequest class. What's somewhat odd here though is that WinInet seems to find no issue with these servers - it's only .NET's Http client that's ultra finicky. So the question then becomes how do you tell HttpWebRequest to ignore certificate errors? In WinInet there used to be a host of flags to do this, but it's not quite so easy with WebRequest. Basically you need to configure the CertificatePolicy on the ServicePointManager by creating a custom policy. Not exactly trivial. Here's the code to hook it up: public bool CreateWebRequestObject(string Url) {    try     {        this.WebRequest =  (HttpWebRequest) System.Net.WebRequest.Create(Url);         if (this.IgnoreCertificateErrors)            ServicePointManager.CertificatePolicy = delegate { return true; };}One thing to watch out for is that this an application global setting. There's one global ServicePointManager and once you set this value any subsequent requests will inherit this policy as well, which may or may not be what you want. So it's probably a good idea to set the policy when the app starts and leave it be - otherwise you may run into odd behavior in some situations especially in multi-thread situations.Another way to deal with this is in you application .config file. Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} <configuration>   <system.net>     <settings>       <servicePointManager           checkCertificateName="false"           checkCertificateRevocationList="false"                />     </settings>   </system.net> </configuration> This seems to work most of the time, although I've seen some situations where it doesn't, but where the code implementation works which is frustrating. The .config settings aren't as inclusive as the programmatic code that can ignore any and all cert errors - shrug. Anyway, the code approach got me past the stopper issue. It still amazes me that theses OFX servers even require this. After all this is financial data we're talking about here. The last thing I want to do is disable extra checks on the certificates. Well I guess I shouldn't be surprised - these are the same companies that apparently don't believe in XML enough to generate valid XML (or even valid SGML for that matter)...© Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  CSharp  HTTP  

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  • Getting the innermost .NET Exception

    - by Rick Strahl
    Here's a trivial but quite useful function that I frequently need in dynamic execution of code: Finding the innermost exception when an exception occurs, because for many operations (for example Reflection invocations or Web Service calls) the top level errors returned can be rather generic. A good example - common with errors in Reflection making a method invocation - is this generic error: Exception has been thrown by the target of an invocation In the debugger it looks like this: In this case this is an AJAX callback, which dynamically executes a method (ExecuteMethod code) which in turn calls into an Amazon Web Service using the old Amazon WSE101 Web service extensions for .NET. An error occurs in the Web Service call and the innermost exception holds the useful error information which in this case points at an invalid web.config key value related to the System.Net connection APIs. The "Exception has been thrown by the target of an invocation" error is the Reflection APIs generic error message that gets fired when you execute a method dynamically and that method fails internally. The messages basically says: "Your code blew up in my face when I tried to run it!". Which of course is not very useful to tell you what actually happened. If you drill down the InnerExceptions eventually you'll get a more detailed exception that points at the original error and code that caused the exception. In the code above the actually useful exception is two innerExceptions down. In most (but not all) cases when inner exceptions are returned, it's the innermost exception that has the information that is really useful. It's of course a fairly trivial task to do this in code, but I do it so frequently that I use a small helper method for this: /// <summary> /// Returns the innermost Exception for an object /// </summary> /// <param name="ex"></param> /// <returns></returns> public static Exception GetInnerMostException(Exception ex) { Exception currentEx = ex; while (currentEx.InnerException != null) { currentEx = currentEx.InnerException; } return currentEx; } This code just loops through all the inner exceptions (if any) and assigns them to a temporary variable until there are no more inner exceptions. The end result is that you get the innermost exception returned from the original exception. It's easy to use this code then in a try/catch handler like this (from the example above) to retrieve the more important innermost exception: object result = null; string stringResult = null; try { if (parameterList != null) // use the supplied parameter list result = helper.ExecuteMethod(methodToCall,target, parameterList.ToArray(), CallbackMethodParameterType.Json,ref attr); else // grab the info out of QueryString Values or POST buffer during parameter parsing // for optimization result = helper.ExecuteMethod(methodToCall, target, null, CallbackMethodParameterType.Json, ref attr); } catch (Exception ex) { Exception activeException = DebugUtils.GetInnerMostException(ex); WriteErrorResponse(activeException.Message, ( HttpContext.Current.IsDebuggingEnabled ? ex.StackTrace : null ) ); return; } Another function that is useful to me from time to time is one that returns all inner exceptions and the original exception as an array: /// <summary> /// Returns an array of the entire exception list in reverse order /// (innermost to outermost exception) /// </summary> /// <param name="ex">The original exception to work off</param> /// <returns>Array of Exceptions from innermost to outermost</returns> public static Exception[] GetInnerExceptions(Exception ex) {     List<Exception> exceptions = new List<Exception>();     exceptions.Add(ex);       Exception currentEx = ex;     while (currentEx.InnerException != null)     {         exceptions.Add(ex);     }       // Reverse the order to the innermost is first     exceptions.Reverse();       return exceptions.ToArray(); } This function loops through all the InnerExceptions and returns them and then reverses the order of the array returning the innermost exception first. This can be useful in certain error scenarios where exceptions stack and you need to display information from more than one of the exceptions in order to create a useful error message. This is rare but certain database exceptions bury their exception info in mutliple inner exceptions and it's easier to parse through them in an array then to manually walk the exception stack. It's also useful if you need to log errors and want to see the all of the error detail from all exceptions. None of this is rocket science, but it's useful to have some helpers that make retrieval of the critical exception info trivial. Resources DebugUtils.cs utility class in the West Wind Web Toolkit© Rick Strahl, West Wind Technologies, 2005-2011Posted in CSharp  .NET  

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  • The dynamic Type in C# Simplifies COM Member Access from Visual FoxPro

    - by Rick Strahl
    I’ve written quite a bit about Visual FoxPro interoperating with .NET in the past both for ASP.NET interacting with Visual FoxPro COM objects as well as Visual FoxPro calling into .NET code via COM Interop. COM Interop with Visual FoxPro has a number of problems but one of them at least got a lot easier with the introduction of dynamic type support in .NET. One of the biggest problems with COM interop has been that it’s been really difficult to pass dynamic objects from FoxPro to .NET and get them properly typed. The only way that any strong typing can occur in .NET for FoxPro components is via COM type library exports of Visual FoxPro components. Due to limitations in Visual FoxPro’s type library support as well as the dynamic nature of the Visual FoxPro language where few things are or can be described in the form of a COM type library, a lot of useful interaction between FoxPro and .NET required the use of messy Reflection code in .NET. Reflection is .NET’s base interface to runtime type discovery and dynamic execution of code without requiring strong typing. In FoxPro terms it’s similar to EVALUATE() functionality albeit with a much more complex API and corresponiding syntax. The Reflection APIs are fairly powerful, but they are rather awkward to use and require a lot of code. Even with the creation of wrapper utility classes for common EVAL() style Reflection functionality dynamically access COM objects passed to .NET often is pretty tedious and ugly. Let’s look at a simple example. In the following code I use some FoxPro code to dynamically create an object in code and then pass this object to .NET. An alternative to this might also be to create a new object on the fly by using SCATTER NAME on a database record. How the object is created is inconsequential, other than the fact that it’s not defined as a COM object – it’s a pure FoxPro object that is passed to .NET. Here’s the code: *** Create .NET COM InstanceloNet = CREATEOBJECT('DotNetCom.DotNetComPublisher') *** Create a Customer Object Instance (factory method) loCustomer = GetCustomer() loCustomer.Name = "Rick Strahl" loCustomer.Company = "West Wind Technologies" loCustomer.creditLimit = 9999999999.99 loCustomer.Address.StreetAddress = "32 Kaiea Place" loCustomer.Address.Phone = "808 579-8342" loCustomer.Address.Email = "[email protected]" *** Pass Fox Object and echo back values ? loNet.PassRecordObject(loObject) RETURN FUNCTION GetCustomer LOCAL loCustomer, loAddress loCustomer = CREATEOBJECT("EMPTY") ADDPROPERTY(loCustomer,"Name","") ADDPROPERTY(loCustomer,"Company","") ADDPROPERTY(loCUstomer,"CreditLimit",0.00) ADDPROPERTY(loCustomer,"Entered",DATETIME()) loAddress = CREATEOBJECT("Empty") ADDPROPERTY(loAddress,"StreetAddress","") ADDPROPERTY(loAddress,"Phone","") ADDPROPERTY(loAddress,"Email","") ADDPROPERTY(loCustomer,"Address",loAddress) RETURN loCustomer ENDFUNC Now prior to .NET 4.0 you’d have to access this object passed to .NET via Reflection and the method code to do this would looks something like this in the .NET component: public string PassRecordObject(object FoxObject) { // *** using raw Reflection string Company = (string) FoxObject.GetType().InvokeMember( "Company", BindingFlags.GetProperty,null, FoxObject,null); // using the easier ComUtils wrappers string Name = (string) ComUtils.GetProperty(FoxObject,"Name"); // Getting Address object – then getting child properties object Address = ComUtils.GetProperty(FoxObject,"Address");    string Street = (string) ComUtils.GetProperty(FoxObject,"StreetAddress"); // using ComUtils 'Ex' functions you can use . Syntax     string StreetAddress = (string) ComUtils.GetPropertyEx(FoxObject,"AddressStreetAddress"); return Name + Environment.NewLine + Company + Environment.NewLine + StreetAddress + Environment.NewLine + " FOX"; } Note that the FoxObject is passed in as type object which has no specific type. Since the object doesn’t exist in .NET as a type signature the object is passed without any specific type information as plain non-descript object. To retrieve a property the Reflection APIs like Type.InvokeMember or Type.GetProperty().GetValue() etc. need to be used. I made this code a little simpler by using the Reflection Wrappers I mentioned earlier but even with those ComUtils calls the code is pretty ugly requiring passing the objects for each call and casting each element. Using .NET 4.0 Dynamic Typing makes this Code a lot cleaner Enter .NET 4.0 and the dynamic type. Replacing the input parameter to the .NET method from type object to dynamic makes the code to access the FoxPro component inside of .NET much more natural: public string PassRecordObjectDynamic(dynamic FoxObject) { // *** using raw Reflection string Company = FoxObject.Company; // *** using the easier ComUtils class string Name = FoxObject.Name; // *** using ComUtils 'ex' functions to use . Syntax string Address = FoxObject.Address.StreetAddress; return Name + Environment.NewLine + Company + Environment.NewLine + Address + Environment.NewLine + " FOX"; } As you can see the parameter is of type dynamic which as the name implies performs Reflection lookups and evaluation on the fly so all the Reflection code in the last example goes away. The code can use regular object ‘.’ syntax to reference each of the members of the object. You can access properties and call methods this way using natural object language. Also note that all the type casts that were required in the Reflection code go away – dynamic types like var can infer the type to cast to based on the target assignment. As long as the type can be inferred by the compiler at compile time (ie. the left side of the expression is strongly typed) no explicit casts are required. Note that although you get to use plain object syntax in the code above you don’t get Intellisense in Visual Studio because the type is dynamic and thus has no hard type definition in .NET . The above example calls a .NET Component from VFP, but it also works the other way around. Another frequent scenario is an .NET code calling into a FoxPro COM object that returns a dynamic result. Assume you have a FoxPro COM object returns a FoxPro Cursor Record as an object: DEFINE CLASS FoxData AS SESSION OlePublic cAppStartPath = "" FUNCTION INIT THIS.cAppStartPath = ADDBS( JustPath(Application.ServerName) ) SET PATH TO ( THIS.cAppStartpath ) ENDFUNC FUNCTION GetRecord(lnPk) LOCAL loCustomer SELECT * FROM tt_Cust WHERE pk = lnPk ; INTO CURSOR TCustomer IF _TALLY < 1 RETURN NULL ENDIF SCATTER NAME loCustomer MEMO RETURN loCustomer ENDFUNC ENDDEFINE If you call this from a .NET application you can now retrieve this data via COM Interop and cast the result as dynamic to simplify the data access of the dynamic FoxPro type that was created on the fly: int pk = 0; int.TryParse(Request.QueryString["id"],out pk); // Create Fox COM Object with Com Callable Wrapper FoxData foxData = new FoxData(); dynamic foxRecord = foxData.GetRecord(pk); string company = foxRecord.Company; DateTime entered = foxRecord.Entered; This code looks simple and natural as it should be – heck you could write code like this in days long gone by in scripting languages like ASP classic for example. Compared to the Reflection code that previously was necessary to run similar code this is much easier to write, understand and maintain. For COM interop and Visual FoxPro operation dynamic type support in .NET 4.0 is a huge improvement and certainly makes it much easier to deal with FoxPro code that calls into .NET. Regardless of whether you’re using COM for calling Visual FoxPro objects from .NET (ASP.NET calling a COM component and getting a dynamic result returned) or whether FoxPro code is calling into a .NET COM component from a FoxPro desktop application. At one point or another FoxPro likely ends up passing complex dynamic data to .NET and for this the dynamic typing makes coding much cleaner and more readable without having to create custom Reflection wrappers. As a bonus the dynamic runtime that underlies the dynamic type is fairly efficient in terms of making Reflection calls especially if members are repeatedly accessed. © Rick Strahl, West Wind Technologies, 2005-2010Posted in COM  FoxPro  .NET  CSharp  

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  • Dynamic Types and DynamicObject References in C#

    - by Rick Strahl
    I've been working a bit with C# custom dynamic types for several customers recently and I've seen some confusion in understanding how dynamic types are referenced. This discussion specifically centers around types that implement IDynamicMetaObjectProvider or subclass from DynamicObject as opposed to arbitrary type casts of standard .NET types. IDynamicMetaObjectProvider types  are treated special when they are cast to the dynamic type. Assume for a second that I've created my own implementation of a custom dynamic type called DynamicFoo which is about as simple of a dynamic class that I can think of:public class DynamicFoo : DynamicObject { Dictionary<string, object> properties = new Dictionary<string, object>(); public string Bar { get; set; } public DateTime Entered { get; set; } public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; if (!properties.ContainsKey(binder.Name)) return false; result = properties[binder.Name]; return true; } public override bool TrySetMember(SetMemberBinder binder, object value) { properties[binder.Name] = value; return true; } } This class has an internal dictionary member and I'm exposing this dictionary member through a dynamic by implementing DynamicObject. This implementation exposes the properties dictionary so the dictionary keys can be referenced like properties (foo.NewProperty = "Cool!"). I override TryGetMember() and TrySetMember() which are fired at runtime every time you access a 'property' on a dynamic instance of this DynamicFoo type. Strong Typing and Dynamic Casting I now can instantiate and use DynamicFoo in a couple of different ways: Strong TypingDynamicFoo fooExplicit = new DynamicFoo(); var fooVar = new DynamicFoo(); These two commands are essentially identical and use strong typing. The compiler generates identical code for both of them. The var statement is merely a compiler directive to infer the type of fooVar at compile time and so the type of fooExplicit is DynamicFoo, just like fooExplicit. This is very static - nothing dynamic about it - and it completely ignores the IDynamicMetaObjectProvider implementation of my class above as it's never used. Using either of these I can access the native properties:DynamicFoo fooExplicit = new DynamicFoo();// static typing assignmentsfooVar.Bar = "Barred!"; fooExplicit.Entered = DateTime.Now; // echo back static values Console.WriteLine(fooVar.Bar); Console.WriteLine(fooExplicit.Entered); but I have no access whatsoever to the properties dictionary. Basically this creates a strongly typed instance of the type with access only to the strongly typed interface. You get no dynamic behavior at all. The IDynamicMetaObjectProvider features don't kick in until you cast the type to dynamic. If I try to access a non-existing property on fooExplicit I get a compilation error that tells me that the property doesn't exist. Again, it's clearly and utterly non-dynamic. Dynamicdynamic fooDynamic = new DynamicFoo(); fooDynamic on the other hand is created as a dynamic type and it's a completely different beast. I can also create a dynamic by simply casting any type to dynamic like this:DynamicFoo fooExplicit = new DynamicFoo(); dynamic fooDynamic = fooExplicit; Note that dynamic typically doesn't require an explicit cast as the compiler automatically performs the cast so there's no need to use as dynamic. Dynamic functionality works at runtime and allows for the dynamic wrapper to look up and call members dynamically. A dynamic type will look for members to access or call in two places: Using the strongly typed members of the object Using theIDynamicMetaObjectProvider Interface methods to access members So rather than statically linking and calling a method or retrieving a property, the dynamic type looks up - at runtime  - where the value actually comes from. It's essentially late-binding which allows runtime determination what action to take when a member is accessed at runtime *if* the member you are accessing does not exist on the object. Class members are checked first before IDynamicMetaObjectProvider interface methods are kick in. All of the following works with the dynamic type:dynamic fooDynamic = new DynamicFoo(); // dynamic typing assignments fooDynamic.NewProperty = "Something new!"; fooDynamic.LastAccess = DateTime.Now; // dynamic assigning static properties fooDynamic.Bar = "dynamic barred"; fooDynamic.Entered = DateTime.Now; // echo back dynamic values Console.WriteLine(fooDynamic.NewProperty); Console.WriteLine(fooDynamic.LastAccess); Console.WriteLine(fooDynamic.Bar); Console.WriteLine(fooDynamic.Entered); The dynamic type can access the native class properties (Bar and Entered) and create and read new ones (NewProperty,LastAccess) all using a single type instance which is pretty cool. As you can see it's pretty easy to create an extensible type this way that can dynamically add members at runtime dynamically. The Alter Ego of IDynamicObject The key point here is that all three statements - explicit, var and dynamic - declare a new DynamicFoo(), but the dynamic declaration results in completely different behavior than the first two simply because the type has been cast to dynamic. Dynamic binding means that the type loses its typical strong typing, compile time features. You can see this easily in the Visual Studio code editor. As soon as you assign a value to a dynamic you lose Intellisense and you see which means there's no Intellisense and no compiler type checking on any members you apply to this instance. If you're new to the dynamic type it might seem really confusing that a single type can behave differently depending on how it is cast, but that's exactly what happens when you use a type that implements IDynamicMetaObjectProvider. Declare the type as its strong type name and you only get to access the native instance members of the type. Declare or cast it to dynamic and you get dynamic behavior which accesses native members plus it uses IDynamicMetaObjectProvider implementation to handle any missing member definitions by running custom code. You can easily cast objects back and forth between dynamic and the original type:dynamic fooDynamic = new DynamicFoo(); fooDynamic.NewProperty = "New Property Value"; DynamicFoo foo = fooDynamic; foo.Bar = "Barred"; Here the code starts out with a dynamic cast and a dynamic assignment. The code then casts back the value to the DynamicFoo. Notice that when casting from dynamic to DynamicFoo and back we typically do not have to specify the cast explicitly - the compiler can induce the type so I don't need to specify as dynamic or as DynamicFoo. Moral of the Story This easy interchange between dynamic and the underlying type is actually super useful, because it allows you to create extensible objects that can expose non-member data stores and expose them as an object interface. You can create an object that hosts a number of strongly typed properties and then cast the object to dynamic and add additional dynamic properties to the same type at runtime. You can easily switch back and forth between the strongly typed instance to access the well-known strongly typed properties and to dynamic for the dynamic properties added at runtime. Keep in mind that dynamic object access has quite a bit of overhead and is definitely slower than strongly typed binding, so if you're accessing the strongly typed parts of your objects you definitely want to use a strongly typed reference. Reserve dynamic for the dynamic members to optimize your code. The real beauty of dynamic is that with very little effort you can build expandable objects or objects that expose different data stores to an object interface. I'll have more on this in my next post when I create a customized and extensible Expando object based on DynamicObject.© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Dynamically creating a Generic Type at Runtime

    - by Rick Strahl
    I learned something new today. Not uncommon, but it's a core .NET runtime feature I simply did not know although I know I've run into this issue a few times and worked around it in other ways. Today there was no working around it and a few folks on Twitter pointed me in the right direction. The question I ran into is: How do I create a type instance of a generic type when I have dynamically acquired the type at runtime? Yup it's not something that you do everyday, but when you're writing code that parses objects dynamically at runtime it comes up from time to time. In my case it's in the bowels of a custom JSON parser. After some thought triggered by a comment today I realized it would be fairly easy to implement two-way Dictionary parsing for most concrete dictionary types. I could use a custom Dictionary serialization format that serializes as an array of key/value objects. Basically I can use a custom type (that matches the JSON signature) to hold my parsed dictionary data and then add it to the actual dictionary when parsing is complete. Generic Types at Runtime One issue that came up in the process was how to figure out what type the Dictionary<K,V> generic parameters take. Reflection actually makes it fairly easy to figure out generic types at runtime with code like this: if (arrayType.GetInterface("IDictionary") != null) { if (arrayType.IsGenericType) { var keyType = arrayType.GetGenericArguments()[0]; var valueType = arrayType.GetGenericArguments()[1]; … } } The GetArrayType method gets passed a type instance that is the array or array-like object that is rendered in JSON as an array (which includes IList, IDictionary, IDataReader and a few others). In my case the type passed would be something like Dictionary<string, CustomerEntity>. So I know what the parent container class type is. Based on the the container type using it's then possible to use GetGenericTypeArguments() to retrieve all the generic types in sequential order of definition (ie. string, CustomerEntity). That's the easy part. Creating a Generic Type and Providing Generic Parameters at RunTime The next problem is how do I get a concrete type instance for the generic type? I know what the type name and I have a type instance is but it's generic, so how do I get a type reference to keyvaluepair<K,V> that is specific to the keyType and valueType above? Here are a couple of things that come to mind but that don't work (and yes I tried that unsuccessfully first): Type elementType = typeof(keyvalue<keyType, valueType>); Type elementType = typeof(keyvalue<typeof(keyType), typeof(valueType)>); The problem is that this explicit syntax expects a type literal not some dynamic runtime value, so both of the above won't even compile. I turns out the way to create a generic type at runtime is using a fancy bit of syntax that until today I was completely unaware of: Type elementType = typeof(keyvalue<,>).MakeGenericType(keyType, valueType); The key is the type(keyvalue<,>) bit which looks weird at best. It works however and produces a non-generic type reference. You can see the difference between the full generic type and the non-typed (?) generic type in the debugger: The nonGenericType doesn't show any type specialization, while the elementType type shows the string, CustomerEntity (truncated above) in the type name. Once the full type reference exists (elementType) it's then easy to create an instance. In my case the parser parses through the JSON and when it completes parsing the value/object it creates a new keyvalue<T,V> instance. Now that I know the element type that's pretty trivial with: // Objects start out null until we find the opening tag resultObject = Activator.CreateInstance(elementType); Here the result object is picked up by the JSON array parser which creates an instance of the child object (keyvalue<K,V>) and then parses and assigns values from the JSON document using the types  key/value property signature. Internally the parser then takes each individually parsed item and adds it to a list of  List<keyvalue<K,V>> items. Parsing through a Generic type when you only have Runtime Type Information When parsing of the JSON array is done, the List needs to be turned into a defacto Dictionary<K,V>. This should be easy since I know that I'm dealing with an IDictionary, and I know the generic types for the key and value. The problem is again though that this needs to happen at runtime which would mean using several Convert.ChangeType() calls in the code to dynamically cast at runtime. Yuk. In the end I decided the easier and probably only slightly slower way to do this is a to use the dynamic type to collect the items and assign them to avoid all the dynamic casting madness: else if (IsIDictionary) { IDictionary dict = Activator.CreateInstance(arrayType) as IDictionary; foreach (dynamic item in items) { dict.Add(item.key, item.value); } return dict; } This code creates an instance of the generic dictionary type first, then loops through all of my custom keyvalue<K,V> items and assigns them to the actual dictionary. By using Dynamic here I can side step all the explicit type conversions that would be required in the three highlighted areas (not to mention that this nested method doesn't have access to the dictionary item generic types here). Static <- -> Dynamic Dynamic casting in a static language like C# is a bitch to say the least. This is one of the few times when I've cursed static typing and the arcane syntax that's required to coax types into the right format. It works but it's pretty nasty code. If it weren't for dynamic that last bit of code would have been a pretty ugly as well with a bunch of Convert.ChangeType() calls to litter the code. Fortunately this type of type convulsion is rather rare and reserved for system level code. It's not every day that you create a string to object parser after all :-)© Rick Strahl, West Wind Technologies, 2005-2011Posted in .NET  CSharp   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Dynamic Code for type casting Generic Types 'generically' in C#

    - by Rick Strahl
    C# is a strongly typed language and while that's a fundamental feature of the language there are more and more situations where dynamic types make a lot of sense. I've written quite a bit about how I use dynamic for creating new type extensions: Dynamic Types and DynamicObject References in C# Creating a dynamic, extensible C# Expando Object Creating a dynamic DataReader for dynamic Property Access Today I want to point out an example of a much simpler usage for dynamic that I use occasionally to get around potential static typing issues in C# code especially those concerning generic types. TypeCasting Generics Generic types have been around since .NET 2.0 I've run into a number of situations in the past - especially with generic types that don't implement specific interfaces that can be cast to - where I've been unable to properly cast an object when it's passed to a method or assigned to a property. Granted often this can be a sign of bad design, but in at least some situations the code that needs to be integrated is not under my control so I have to make due with what's available or the parent object is too complex or intermingled to be easily refactored to a new usage scenario. Here's an example that I ran into in my own RazorHosting library - so I have really no excuse, but I also don't see another clean way around it in this case. A Generic Example Imagine I've implemented a generic type like this: public class RazorEngine<TBaseTemplateType> where TBaseTemplateType : RazorTemplateBase, new() You can now happily instantiate new generic versions of this type with custom template bases or even a non-generic version which is implemented like this: public class RazorEngine : RazorEngine<RazorTemplateBase> { public RazorEngine() : base() { } } To instantiate one: var engine = new RazorEngine<MyCustomRazorTemplate>(); Now imagine that the template class receives a reference to the engine when it's instantiated. This code is fired as part of the Engine pipeline when it gets ready to execute the template. It instantiates the template and assigns itself to the template: var template = new TBaseTemplateType() { Engine = this } The problem here is that possibly many variations of RazorEngine<T> can be passed. I can have RazorTemplateBase, RazorFolderHostTemplateBase, CustomRazorTemplateBase etc. as generic parameters and the Engine property has to reflect that somehow. So, how would I cast that? My first inclination was to use an interface on the engine class and then cast to the interface.  Generally that works, but unfortunately here the engine class is generic and has a few members that require the template type in the member signatures. So while I certainly can implement an interface: public interface IRazorEngine<TBaseTemplateType> it doesn't really help for passing this generically templated object to the template class - I still can't cast it if multiple differently typed versions of the generic type could be passed. I have the exact same issue in that I can't specify a 'generic' generic parameter, since there's no underlying base type that's common. In light of this I decided on using object and the following syntax for the property (and the same would be true for a method parameter): public class RazorTemplateBase :MarshalByRefObject,IDisposable { public object Engine {get;set; } } Now because the Engine property is a non-typed object, when I need to do something with this value, I still have no way to cast it explicitly. What I really would need is: public RazorEngine<> Engine { get; set; } but that's not possible. Dynamic to the Rescue Luckily with the dynamic type this sort of thing can be mitigated fairly easily. For example here's a method that uses the Engine property and uses the well known class interface by simply casting the plain object reference to dynamic and then firing away on the properties and methods of the base template class that are common to all templates:/// <summary> /// Allows rendering a dynamic template from a string template /// passing in a model. This is like rendering a partial /// but providing the input as a /// </summary> public virtual string RenderTemplate(string template,object model) { if (template == null) return string.Empty; // if there's no template markup if(!template.Contains("@")) return template; // use dynamic to get around generic type casting dynamic engine = Engine; string result = engine.RenderTemplate(template, model); if (result == null) throw new ApplicationException("RenderTemplate failed: " + engine.ErrorMessage); return result; } Prior to .NET 4.0  I would have had to use Reflection for this sort of thing which would have a been a heck of a lot more verbose, but dynamic makes this so much easier and cleaner and in this case at least the overhead is negliable since it's a single dynamic operation on an otherwise very complex operation call. Dynamic as  a Bailout Sometimes this sort of thing often reeks of a design flaw, and I agree that in hindsight this could have been designed differently. But as is often the case this particular scenario wasn't planned for originally and removing the generic signatures from the base type would break a ton of other code in the framework. Given the existing fairly complex engine design, refactoring an interface to remove generic types just to make this particular code work would have been overkill. Instead dynamic provides a nice and simple and relatively clean solution. Now if there were many other places where this occurs I would probably consider reworking the code to make this cleaner but given this isolated instance and relatively low profile operation use of dynamic seems a valid choice for me. This solution really works anywhere where you might end up with an inheritance structure that doesn't have a common base or interface that is sufficient. In the example above I know what I'm getting but there's no common base type that I can cast to. All that said, it's a good idea to think about use of dynamic before you rush in. In many situations there are alternatives that can still work with static typing. Dynamic definitely has some overhead compared to direct static access of objects, so if possible we should definitely stick to static typing. In the example above the application already uses dynamics extensively for dynamic page page templating and passing models around so introducing dynamics here has very little additional overhead. The operation itself also fires of a fairly resource heavy operation where the overhead of a couple of dynamic member accesses are not a performance issue. So, what's your experience with dynamic as a bailout mechanism? © Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Dynamic Type to do away with Reflection

    - by Rick Strahl
    The dynamic type in C# 4.0 is a welcome addition to the language. One thing I’ve been doing a lot with it is to remove explicit Reflection code that’s often necessary when you ‘dynamically’ need to walk and object hierarchy. In the past I’ve had a number of ReflectionUtils that used string based expressions to walk an object hierarchy. With the introduction of dynamic much of the ReflectionUtils code can be removed for cleaner code that runs considerably faster to boot. The old Way - Reflection Here’s a really contrived example, but assume for a second, you’d want to dynamically retrieve a Page.Request.Url.AbsoluteUrl based on a Page instance in an ASP.NET Web Page request. The strongly typed version looks like this: string path = Page.Request.Url.AbsolutePath; Now assume for a second that Page wasn’t available as a strongly typed instance and all you had was an object reference to start with and you couldn’t cast it (right I said this was contrived :-)) If you’re using raw Reflection code to retrieve this you’d end up writing 3 sets of Reflection calls using GetValue(). Here’s some internal code I use to retrieve Property values as part of ReflectionUtils: /// <summary> /// Retrieve a property value from an object dynamically. This is a simple version /// that uses Reflection calls directly. It doesn't support indexers. /// </summary> /// <param name="instance">Object to make the call on</param> /// <param name="property">Property to retrieve</param> /// <returns>Object - cast to proper type</returns> public static object GetProperty(object instance, string property) { return instance.GetType().GetProperty(property, ReflectionUtils.MemberAccess).GetValue(instance, null); } If you want more control over properties and support both fields and properties as well as array indexers a little more work is required: /// <summary> /// Parses Properties and Fields including Array and Collection references. /// Used internally for the 'Ex' Reflection methods. /// </summary> /// <param name="Parent"></param> /// <param name="Property"></param> /// <returns></returns> private static object GetPropertyInternal(object Parent, string Property) { if (Property == "this" || Property == "me") return Parent; object result = null; string pureProperty = Property; string indexes = null; bool isArrayOrCollection = false; // Deal with Array Property if (Property.IndexOf("[") > -1) { pureProperty = Property.Substring(0, Property.IndexOf("[")); indexes = Property.Substring(Property.IndexOf("[")); isArrayOrCollection = true; } // Get the member MemberInfo member = Parent.GetType().GetMember(pureProperty, ReflectionUtils.MemberAccess)[0]; if (member.MemberType == MemberTypes.Property) result = ((PropertyInfo)member).GetValue(Parent, null); else result = ((FieldInfo)member).GetValue(Parent); if (isArrayOrCollection) { indexes = indexes.Replace("[", string.Empty).Replace("]", string.Empty); if (result is Array) { int Index = -1; int.TryParse(indexes, out Index); result = CallMethod(result, "GetValue", Index); } else if (result is ICollection) { if (indexes.StartsWith("\"")) { // String Index indexes = indexes.Trim('\"'); result = CallMethod(result, "get_Item", indexes); } else { // assume numeric index int index = -1; int.TryParse(indexes, out index); result = CallMethod(result, "get_Item", index); } } } return result; } /// <summary> /// Returns a property or field value using a base object and sub members including . syntax. /// For example, you can access: oCustomer.oData.Company with (this,"oCustomer.oData.Company") /// This method also supports indexers in the Property value such as: /// Customer.DataSet.Tables["Customers"].Rows[0] /// </summary> /// <param name="Parent">Parent object to 'start' parsing from. Typically this will be the Page.</param> /// <param name="Property">The property to retrieve. Example: 'Customer.Entity.Company'</param> /// <returns></returns> public static object GetPropertyEx(object Parent, string Property) { Type type = Parent.GetType(); int at = Property.IndexOf("."); if (at < 0) { // Complex parse of the property return GetPropertyInternal(Parent, Property); } // Walk the . syntax - split into current object (Main) and further parsed objects (Subs) string main = Property.Substring(0, at); string subs = Property.Substring(at + 1); // Retrieve the next . section of the property object sub = GetPropertyInternal(Parent, main); // Now go parse the left over sections return GetPropertyEx(sub, subs); } As you can see there’s a fair bit of code involved into retrieving a property or field value reliably especially if you want to support array indexer syntax. This method is then used by a variety of routines to retrieve individual properties including one called GetPropertyEx() which can walk the dot syntax hierarchy easily. Anyway with ReflectionUtils I can  retrieve Page.Request.Url.AbsolutePath using code like this: string url = ReflectionUtils.GetPropertyEx(Page, "Request.Url.AbsolutePath") as string; This works fine, but is bulky to write and of course requires that I use my custom routines. It’s also quite slow as the code in GetPropertyEx does all sorts of string parsing to figure out which members to walk in the hierarchy. Enter dynamic – way easier! .NET 4.0’s dynamic type makes the above really easy. The following code is all that it takes: object objPage = Page; // force to object for contrivance :) dynamic page = objPage; // convert to dynamic from untyped object string scriptUrl = page.Request.Url.AbsolutePath; The dynamic type assignment in the first two lines turns the strongly typed Page object into a dynamic. The first assignment is just part of the contrived example to force the strongly typed Page reference into an untyped value to demonstrate the dynamic member access. The next line then just creates the dynamic type from the Page reference which allows you to access any public properties and methods easily. It also lets you access any child properties as dynamic types so when you look at Intellisense you’ll see something like this when typing Request.: In other words any dynamic value access on an object returns another dynamic object which is what allows the walking of the hierarchy chain. Note also that the result value doesn’t have to be explicitly cast as string in the code above – the compiler is perfectly happy without the cast in this case inferring the target type based on the type being assigned to. The dynamic conversion automatically handles the cast when making the final assignment which is nice making for natural syntnax that looks *exactly* like the fully typed syntax, but is completely dynamic. Note that you can also use indexers in the same natural syntax so the following also works on the dynamic page instance: string scriptUrl = page.Request.ServerVariables["SCRIPT_NAME"]; The dynamic type is going to make a lot of Reflection code go away as it’s simply so much nicer to be able to use natural syntax to write out code that previously required nasty Reflection syntax. Another interesting thing about the dynamic type is that it actually works considerably faster than Reflection. Check out the following methods that check performance: void Reflection() { Stopwatch stop = new Stopwatch(); stop.Start(); for (int i = 0; i < reps; i++) { // string url = ReflectionUtils.GetProperty(Page,"Title") as string;// "Request.Url.AbsolutePath") as string; string url = Page.GetType().GetProperty("Title", ReflectionUtils.MemberAccess).GetValue(Page, null) as string; } stop.Stop(); Response.Write("Reflection: " + stop.ElapsedMilliseconds.ToString()); } void Dynamic() { Stopwatch stop = new Stopwatch(); stop.Start(); dynamic page = Page; for (int i = 0; i < reps; i++) { string url = page.Title; //Request.Url.AbsolutePath; } stop.Stop(); Response.Write("Dynamic: " + stop.ElapsedMilliseconds.ToString()); } The dynamic code runs in 4-5 milliseconds while the Reflection code runs around 200+ milliseconds! There’s a bit of overhead in the first dynamic object call but subsequent calls are blazing fast and performance is actually much better than manual Reflection. Dynamic is definitely a huge win-win situation when you need dynamic access to objects at runtime.© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  

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  • Back to Basics: When does a .NET Assembly Dependency get loaded

    - by Rick Strahl
    When we work on typical day to day applications, it's easy to forget some of the core features of the .NET framework. For me personally it's been a long time since I've learned about some of the underlying CLR system level services even though I rely on them on a daily basis. I often think only about high level application constructs and/or high level framework functionality, but the low level stuff is often just taken for granted. Over the last week at DevConnections I had all sorts of low level discussions with other developers about the inner workings of this or that technology (especially in light of my Low Level ASP.NET Architecture talk and the Razor Hosting talk). One topic that came up a couple of times and ended up a point of confusion even amongst some seasoned developers (including some folks from Microsoft <snicker>) is when assemblies actually load into a .NET process. There are a number of different ways that assemblies are loaded in .NET. When you create a typical project assemblies usually come from: The Assembly reference list of the top level 'executable' project The Assembly references of referenced projects Dynamically loaded at runtime via AppDomain/Reflection loading In addition .NET automatically loads mscorlib (most of the System namespace) the boot process that hosts the .NET runtime in EXE apps, or some other kind of runtime hosting environment (runtime hosting in servers like IIS, SQL Server or COM Interop). In hosting environments the runtime host may also pre-load a bunch of assemblies on its own (for example the ASP.NET host requires all sorts of assemblies just to run itself, before ever routing into your user specific code). Assembly Loading The most obvious source of loaded assemblies is the top level application's assembly reference list. You can add assembly references to a top level application and those assembly references are then available to the application. In a nutshell, referenced assemblies are not immediately loaded - they are loaded on the fly as needed. So regardless of whether you have an assembly reference in a top level project, or a dependent assembly assemblies typically load on an as needed basis, unless explicitly loaded by user code. The same is true of dependent assemblies. To check this out I ran a simple test: I have a utility assembly Westwind.Utilities which is a general purpose library that can work in any type of project. Due to a couple of small requirements for encoding and a logging piece that allows logging Web content (dependency on HttpContext.Current) this utility library has a dependency on System.Web. Now System.Web is a pretty large assembly and generally you'd want to avoid adding it to a non-Web project if it can be helped. So I created a Console Application that loads my utility library: You can see that the top level Console app a reference to Westwind.Utilities and System.Data (beyond the core .NET libs). The Westwind.Utilities project on the other hand has quite a few dependencies including System.Web. I then add a main program that accesses only a simple utillity method in the Westwind.Utilities library that doesn't require any of the classes that access System.Web: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); } StringUtils.NewStringId() calls into Westwind.Utilities, but it doesn't rely on System.Web. Any guesses what the assembly list looks like when I stop the code on the ReadLine() command? I'll wait here while you think about it… … … So, when I stop on ReadLine() and then fire up Process Explorer and check the assembly list I get: We can see here that .NET has not actually loaded any of the dependencies of the Westwind.Utilities assembly. Also not loaded is the top level System.Data reference even though it's in the dependent assembly list of the top level project. Since this particular function I called only uses core System functionality (contained in mscorlib) there's in fact nothing else loaded beyond the main application and my Westwind.Utilities assembly that contains the method accessed. None of the dependencies of Westwind.Utilities loaded. If you were to open the assembly in a disassembler like Reflector or ILSpy, you would however see all the compiled in dependencies. The referenced assemblies are in the dependency list and they are loadable, but they are not immediately loaded by the application. In other words the C# compiler and .NET linker are smart enough to figure out the dependencies based on the code that actually is referenced from your application and any dependencies cascading down into the dependencies from your top level application into the referenced assemblies. In the example above the usage requirement is pretty obvious since I'm only calling a single static method and then exiting the app, but in more complex applications these dependency relationships become very complicated - however it's all taken care of by the compiler and linker figuring out what types and members are actually referenced and including only those assemblies that are in fact referenced in your code or required by any of your dependencies. The good news here is: That if you are referencing an assembly that has a dependency on something like System.Web in a few places that are not actually accessed by any of your code or any dependent assembly code that you are calling, that assembly is never loaded into memory! Some Hosting Environments pre-load Assemblies The load behavior can vary however. In Console and desktop applications we have full control over assembly loading so we see the core CLR behavior. However other environments like ASP.NET for example will preload referenced assemblies explicitly as part of the startup process - primarily to minimize load conflicts. Specifically ASP.NET pre-loads all assemblies referenced in the assembly list and the /bin folder. So in Web applications it definitely pays to minimize your top level assemblies if they are not used. Understanding when Assemblies Load To clarify and see it actually happen what I described in the first example , let's look at a couple of other scenarios. To see assemblies loading at runtime in real time lets create a utility function to print out loaded assemblies to the console: public static void PrintAssemblies() { var assemblies = AppDomain.CurrentDomain.GetAssemblies(); foreach (var assembly in assemblies) { Console.WriteLine(assembly.GetName()); } } Now let's look at the first scenario where I have class method that references internally uses System.Web. In the first scenario lets add a method to my main program like this: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.ReadLine(); PrintAssemblies(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } UpdateFromWebRequest() internally accesses HttpContext.Current to read some information of the ASP.NET Request object so it clearly needs a reference System.Web to work. In this first example, the method that holds the calling code is never called, but exists as a static method that can potentially be called externally at some point. What do you think will happen here with the assembly loading? Will System.Web load in this example? No - it doesn't. Because the WebLogEntry() method is never called by the mainline application (or anywhere else) System.Web is not loaded. .NET dynamically loads assemblies as code that needs it is called. No code references the WebLogEntry() method and so System.Web is never loaded. Next, let's add the call to this method, which should trigger System.Web to be loaded because a dependency exists. Let's change the code to: static void Main(string[] args) { Console.WriteLine(StringUtils.NewStringId()); Console.WriteLine("--- Before:"); PrintAssemblies(); WebLogEntry(); Console.WriteLine("--- After:"); PrintAssemblies(); Console.ReadLine(); } public static void WebLogEntry() { var entry = new WebLogEntry(); entry.UpdateFromRequest(); Console.WriteLine(entry.QueryString); } Looking at the code now, when do you think System.Web will be loaded? Will the before list include it? Yup System.Web gets loaded, but only after it's actually referenced. In fact, just until before the call to UpdateFromRequest() System.Web is not loaded - it only loads when the method is actually called and requires the reference in the executing code. Moral of the Story So what have we learned - or maybe remembered again? Dependent Assembly References are not pre-loaded when an application starts (by default) Dependent Assemblies that are not referenced by executing code are never loaded Dependent Assemblies are just in time loaded when first referenced in code All of this is nothing new - .NET has always worked like this. But it's good to have a refresher now and then and go through the exercise of seeing it work in action. It's not one of those things we think about everyday, and as I found out last week, I couldn't remember exactly how it worked since it's been so long since I've learned about this. And apparently I'm not the only one as several other people I had discussions with in relation to loaded assemblies also didn't recall exactly what should happen or assumed incorrectly that just having a reference automatically loads the assembly. The moral of the story for me is: Trying at all costs to eliminate an assembly reference from a component is not quite as important as it's often made out to be. For example, the Westwind.Utilities module described above has a logging component, including a Web specific logging entry that supports pulling information from the active HTTP Context. Adding that feature requires a reference to System.Web. Should I worry about this in the scope of this library? Probably not, because if I don't use that one class of nearly a hundred, System.Web never gets pulled into the parent process. IOW, System.Web only loads when I use that specific feature and if I am, well I clearly have to be running in a Web environment anyway to use it realistically. The alternative would be considerably uglier: Pulling out the WebLogEntry class and sticking it into another assembly and breaking up the logging code. In this case - definitely not worth it. So, .NET definitely goes through some pretty nifty optimizations to ensure that it loads only what it needs and in most cases you can just rely on .NET to do the right thing. Sometimes though assembly loading can go wrong (especially when signed and versioned local assemblies are involved), but that's subject for a whole other post…© Rick Strahl, West Wind Technologies, 2005-2012Posted in .NET  CSharp   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Creating a Dynamic DataRow for easier DataRow Syntax

    - by Rick Strahl
    I've been thrown back into an older project that uses DataSets and DataRows as their entity storage model. I have several applications internally that I still maintain that run just fine (and I sometimes wonder if this wasn't easier than all this ORM crap we deal with with 'newer' improved technology today - but I disgress) but use this older code. For the most part DataSets/DataTables/DataRows are abstracted away in a pseudo entity model, but in some situations like queries DataTables and DataRows are still surfaced to the business layer. Here's an example. Here's a business object method that runs dynamic query and the code ends up looping over the result set using the ugly DataRow Array syntax:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { string title = row["title"] as string; string safeTitle = row["safeTitle"] as string; int pk = (int)row["pk"]; string newSafeTitle = this.GetSafeTitle(title); if (newSafeTitle != safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set [email protected] where [email protected]", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",pk) ); result++; } } return result; } The problem with looping over DataRow objecs is two fold: The array syntax is tedious to type and not real clear to look at, and explicit casting is required in order to do anything useful with the values. I've highlighted the place where this matters. Using the DynamicDataRow class I'll show in a minute this code can be changed to look like this:public int UpdateAllSafeTitles() { int result = this.Execute("select pk, title, safetitle from " + Tablename + " where EntryType=1", "TPks"); if (result < 0) return result; result = 0; foreach (DataRow row in this.DataSet.Tables["TPks"].Rows) { dynamic entry = new DynamicDataRow(row); string newSafeTitle = this.GetSafeTitle(entry.title); if (newSafeTitle != entry.safeTitle) { this.ExecuteNonQuery("update " + this.Tablename + " set [email protected] where [email protected]", this.CreateParameter("@safeTitle",newSafeTitle), this.CreateParameter("@pk",entry.pk) ); result++; } } return result; } The code looks much a bit more natural and describes what's happening a little nicer as well. Well, using the new dynamic features in .NET it's actually quite easy to implement the DynamicDataRow class. Creating your own custom Dynamic Objects .NET 4.0 introduced the Dynamic Language Runtime (DLR) and opened up a whole bunch of new capabilities for .NET applications. The dynamic type is an easy way to avoid Reflection and directly access members of 'dynamic' or 'late bound' objects at runtime. There's a lot of very subtle but extremely useful stuff that dynamic does (especially for COM Interop scenearios) but in its simplest form it often allows you to do away with manual Reflection at runtime. In addition you can create DynamicObject implementations that can perform  custom interception of member accesses and so allow you to provide more natural access to more complex or awkward data structures like the DataRow that I use as an example here. Bascially you can subclass DynamicObject and then implement a few methods (TryGetMember, TrySetMember, TryInvokeMember) to provide the ability to return dynamic results from just about any data structure using simple property/method access. In the code above, I created a custom DynamicDataRow class which inherits from DynamicObject and implements only TryGetMember and TrySetMember. Here's what simple class looks like:/// <summary> /// This class provides an easy way to turn a DataRow /// into a Dynamic object that supports direct property /// access to the DataRow fields. /// /// The class also automatically fixes up DbNull values /// (null into .NET and DbNUll to DataRow) /// </summary> public class DynamicDataRow : DynamicObject { /// <summary> /// Instance of object passed in /// </summary> DataRow DataRow; /// <summary> /// Pass in a DataRow to work off /// </summary> /// <param name="instance"></param> public DynamicDataRow(DataRow dataRow) { DataRow = dataRow; } /// <summary> /// Returns a value from a DataRow items array. /// If the field doesn't exist null is returned. /// DbNull values are turned into .NET nulls. /// /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; try { result = DataRow[binder.Name]; if (result == DBNull.Value) result = null; return true; } catch { } result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { try { if (value == null) value = DBNull.Value; DataRow[binder.Name] = value; return true; } catch {} return false; } } To demonstrate the basic features here's a short test: [TestMethod] [ExpectedException(typeof(RuntimeBinderException))] public void BasicDataRowTests() { DataTable table = new DataTable("table"); table.Columns.Add( new DataColumn() { ColumnName = "Name", DataType=typeof(string) }); table.Columns.Add( new DataColumn() { ColumnName = "Entered", DataType=typeof(DateTime) }); table.Columns.Add(new DataColumn() { ColumnName = "NullValue", DataType = typeof(string) }); DataRow row = table.NewRow(); DateTime now = DateTime.Now; row["Name"] = "Rick"; row["Entered"] = now; row["NullValue"] = null; // converted in DbNull dynamic drow = new DynamicDataRow(row); string name = drow.Name; DateTime entered = drow.Entered; string nulled = drow.NullValue; Assert.AreEqual(name, "Rick"); Assert.AreEqual(entered,now); Assert.IsNull(nulled); // this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); } The DynamicDataRow requires a custom constructor that accepts a single parameter that sets the DataRow. Once that's done you can access property values that match the field names. Note that types are automatically converted - no type casting is needed in the code you write. The class also automatically converts DbNulls to regular nulls and vice versa which is something that makes it much easier to deal with data returned from a database. What's cool here isn't so much the functionality - even if I'd prefer to leave DataRow behind ASAP -  but the fact that we can create a dynamic type that uses a DataRow as it's 'DataSource' to serve member values. It's pretty useful feature if you think about it, especially given how little code it takes to implement. By implementing these two simple methods we get to provide two features I was complaining about at the beginning that are missing from the DataRow: Direct Property Syntax Automatic Type Casting so no explicit casts are required Caveats As cool and easy as this functionality is, it's important to understand that it doesn't come for free. The dynamic features in .NET are - well - dynamic. Which means they are essentially evaluated at runtime (late bound). Rather than static typing where everything is compiled and linked by the compiler/linker, member invokations are looked up at runtime and essentially call into your custom code. There's some overhead in this. Direct invocations - the original code I showed - is going to be faster than the equivalent dynamic code. However, in the above code the difference of running the dynamic code and the original data access code was very minor. The loop running over 1500 result records took on average 13ms with the original code and 14ms with the dynamic code. Not exactly a serious performance bottleneck. One thing to remember is that Microsoft optimized the DLR code significantly so that repeated calls to the same operations are routed very efficiently which actually makes for very fast evaluation. The bottom line for performance with dynamic code is: Make sure you test and profile your code if you think that there might be a performance issue. However, in my experience with dynamic types so far performance is pretty good for repeated operations (ie. in loops). While usually a little slower the perf hit is a lot less typically than equivalent Reflection work. Although the code in the second example looks like standard object syntax, dynamic is not static code. It's evaluated at runtime and so there's no type recognition until runtime. This means no Intellisense at development time, and any invalid references that call into 'properties' (ie. fields in the DataRow) that don't exist still cause runtime errors. So in the case of the data row you still get a runtime error if you mistype a column name:// this should throw a RuntimeBinderException Assert.AreEqual(entered,drow.enteredd); Dynamic - Lots of uses The arrival of Dynamic types in .NET has been met with mixed emotions. Die hard .NET developers decry dynamic types as an abomination to the language. After all what dynamic accomplishes goes against all that a static language is supposed to provide. On the other hand there are clearly scenarios when dynamic can make life much easier (COM Interop being one place). Think of the possibilities. What other data structures would you like to expose to a simple property interface rather than some sort of collection or dictionary? And beyond what I showed here you can also implement 'Method missing' behavior on objects with InvokeMember which essentially allows you to create dynamic methods. It's all very flexible and maybe just as important: It's easy to do. There's a lot of power hidden in this seemingly simple interface. Your move…© Rick Strahl, West Wind Technologies, 2005-2011Posted in CSharp  .NET   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Translating with Google Translate without API and C# Code

    - by Rick Strahl
    Some time back I created a data base driven ASP.NET Resource Provider along with some tools that make it easy to edit ASP.NET resources interactively in a Web application. One of the small helper features of the interactive resource admin tool is the ability to do simple translations using both Google Translate and Babelfish. Here's what this looks like in the resource administration form: When a resource is displayed, the user can click a Translate button and it will show the current resource text and then lets you set the source and target languages to translate. The Go button fires the translation for both Google and Babelfish and displays them - pressing use then changes the language of the resource to the target language and sets the resource value to the newly translated value. It's a nice and quick way to get a quick translation going. Ch… Ch… Changes Originally, both implementations basically did some screen scraping of the interactive Web sites and retrieved translated text out of result HTML. Screen scraping is always kind of an iffy proposition as content can be changed easily, but surprisingly that code worked for many years without fail. Recently however, Google at least changed their input pages to use AJAX callbacks and the page updates no longer worked the same way. End result: The Google translate code was broken. Now, Google does have an official API that you can access, but the API is being deprecated and you actually need to have an API key. Since I have public samples that people can download the API key is an issue if I want people to have the samples work out of the box - the only way I could even do this is by sharing my API key (not allowed).   However, after a bit of spelunking and playing around with the public site however I found that Google's interactive translate page actually makes callbacks using plain public access without an API key. By intercepting some of those AJAX calls and calling them directly from code I was able to get translation back up and working with minimal fuss, by parsing out the JSON these AJAX calls return. I don't think this particular Warning: This is hacky code, but after a fair bit of testing I found this to work very well with all sorts of languages and accented and escaped text etc. as long as you stick to small blocks of translated text. I thought I'd share it in case anybody else had been relying on a screen scraping mechanism like I did and needed a non-API based replacement. Here's the code: /// <summary> /// Translates a string into another language using Google's translate API JSON calls. /// <seealso>Class TranslationServices</seealso> /// </summary> /// <param name="Text">Text to translate. Should be a single word or sentence.</param> /// <param name="FromCulture"> /// Two letter culture (en of en-us, fr of fr-ca, de of de-ch) /// </param> /// <param name="ToCulture"> /// Two letter culture (as for FromCulture) /// </param> public string TranslateGoogle(string text, string fromCulture, string toCulture) { fromCulture = fromCulture.ToLower(); toCulture = toCulture.ToLower(); // normalize the culture in case something like en-us was passed // retrieve only en since Google doesn't support sub-locales string[] tokens = fromCulture.Split('-'); if (tokens.Length > 1) fromCulture = tokens[0]; // normalize ToCulture tokens = toCulture.Split('-'); if (tokens.Length > 1) toCulture = tokens[0]; string url = string.Format(@"http://translate.google.com/translate_a/t?client=j&text={0}&hl=en&sl={1}&tl={2}", HttpUtility.UrlEncode(text),fromCulture,toCulture); // Retrieve Translation with HTTP GET call string html = null; try { WebClient web = new WebClient(); // MUST add a known browser user agent or else response encoding doen't return UTF-8 (WTF Google?) web.Headers.Add(HttpRequestHeader.UserAgent, "Mozilla/5.0"); web.Headers.Add(HttpRequestHeader.AcceptCharset, "UTF-8"); // Make sure we have response encoding to UTF-8 web.Encoding = Encoding.UTF8; html = web.DownloadString(url); } catch (Exception ex) { this.ErrorMessage = Westwind.Globalization.Resources.Resources.ConnectionFailed + ": " + ex.GetBaseException().Message; return null; } // Extract out trans":"...[Extracted]...","from the JSON string string result = Regex.Match(html, "trans\":(\".*?\"),\"", RegexOptions.IgnoreCase).Groups[1].Value; if (string.IsNullOrEmpty(result)) { this.ErrorMessage = Westwind.Globalization.Resources.Resources.InvalidSearchResult; return null; } //return WebUtils.DecodeJsString(result); // Result is a JavaScript string so we need to deserialize it properly JavaScriptSerializer ser = new JavaScriptSerializer(); return ser.Deserialize(result, typeof(string)) as string; } To use the code is straightforward enough - simply provide a string to translate and a pair of two letter source and target languages: string result = service.TranslateGoogle("Life is great and one is spoiled when it goes on and on and on", "en", "de"); TestContext.WriteLine(result); How it works The code to translate is fairly straightforward. It basically uses the URL I snagged from the Google Translate Web Page slightly changed to return a JSON result (&client=j) instead of the funky nested PHP style JSON array that the default returns. The JSON result returned looks like this: {"sentences":[{"trans":"Das Leben ist großartig und man wird verwöhnt, wenn es weiter und weiter und weiter geht","orig":"Life is great and one is spoiled when it goes on and on and on","translit":"","src_translit":""}],"src":"en","server_time":24} I use WebClient to make an HTTP GET call to retrieve the JSON data and strip out part of the full JSON response that contains the actual translated text. Since this is a JSON response I need to deserialize the JSON string in case it's encoded (for upper/lower ASCII chars or quotes etc.). Couple of odd things to note in this code: First note that a valid user agent string must be passed (or at least one starting with a common browser identification - I use Mozilla/5.0). Without this Google doesn't encode the result with UTF-8, but instead uses a ISO encoding that .NET can't easily decode. Google seems to ignore the character set header and use the user agent instead which is - odd to say the least. The other is that the code returns a full JSON response. Rather than use the full response and decode it into a custom type that matches Google's result object, I just strip out the translated text. Yeah I know that's hacky but avoids an extra type and firing up the JavaScript deserializer. My internal version uses a small DecodeJsString() method to decode Javascript without the overhead of a full JSON parser. It's obviously not rocket science but as mentioned above what's nice about it is that it works without an Google API key. I can't vouch on how many translates you can do before there are cut offs but in my limited testing running a few stress tests on a Web server under load I didn't run into any problems. Limitations There are some restrictions with this: It only works on single words or single sentences - multiple sentences (delimited by .) are cut off at the ".". There is also a length limitation which appears to happen at around 220 characters or so. While that may not sound  like much for typical word or phrase translations this this is plenty of length. Use with a grain of salt - Google seems to be trying to limit their exposure to usage of the Translate APIs so this code might break in the future, but for now at least it works. FWIW, I also found that Google's translation is not as good as Babelfish, especially for contextual content like sentences. Google is faster, but Babelfish tends to give better translations. This is why in my translation tool I show both Google and Babelfish values retrieved. You can check out the code for this in the West Wind West Wind Web Toolkit's TranslationService.cs file which contains both the Google and Babelfish translation code pieces. Ironically the Babelfish code has been working forever using screen scraping and continues to work just fine today. I think it's a good idea to have multiple translation providers in case one is down or changes its format, hence the dual display in my translation form above. I hope this has been helpful to some of you - I've actually had many small uses for this code in a number of applications and it's sweet to have a simple routine that performs these operations for me easily. Resources Live Localization Sample Localization Resource Provider Administration form that includes options to translate text using Google and Babelfish interactively. TranslationService.cs The full source code in the West Wind West Wind Web Toolkit's Globalization library that contains the translation code. © Rick Strahl, West Wind Technologies, 2005-2011Posted in CSharp  HTTP   Tweet (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • .NET WebRequest.PreAuthenticate not quite what it sounds like

    - by Rick Strahl
    I’ve run into the  problem a few times now: How to pre-authenticate .NET WebRequest calls doing an HTTP call to the server – essentially send authentication credentials on the very first request instead of waiting for a server challenge first? At first glance this sound like it should be easy: The .NET WebRequest object has a PreAuthenticate property which sounds like it should force authentication credentials to be sent on the first request. Looking at the MSDN example certainly looks like it does: http://msdn.microsoft.com/en-us/library/system.net.webrequest.preauthenticate.aspx Unfortunately the MSDN sample is wrong. As is the text of the Help topic which incorrectly leads you to believe that PreAuthenticate… wait for it - pre-authenticates. But it doesn’t allow you to set credentials that are sent on the first request. What this property actually does is quite different. It doesn’t send credentials on the first request but rather caches the credentials ONCE you have already authenticated once. Http Authentication is based on a challenge response mechanism typically where the client sends a request and the server responds with a 401 header requesting authentication. So the client sends a request like this: GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive and the server responds with: HTTP/1.1 401 Unauthorized Cache-Control: private Content-Type: text/html; charset=utf-8 Server: Microsoft-IIS/7.5 WWW-Authenticate: basic realm=rasnote" X-AspNet-Version: 2.0.50727 WWW-Authenticate: Negotiate WWW-Authenticate: NTLM WWW-Authenticate: Basic realm="rasnote" X-Powered-By: ASP.NET Date: Tue, 27 Oct 2009 00:58:20 GMT Content-Length: 5163 plus the actual error message body. The client then is responsible for re-sending the current request with the authentication token information provided (in this case Basic Auth): GET /wconnect/admin/wc.wc?_maintain~ShowStatus HTTP/1.1 Host: rasnote User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506) Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en,de;q=0.7,en-us;q=0.3 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive Cookie: TimeTrakker=2HJ1998WH06696; WebLogCommentUser=Rick Strahl|http://www.west-wind.com/|[email protected]; WebStoreUser=b8bd0ed9 Authorization: Basic cgsf12aDpkc2ZhZG1zMA== Once the authorization info is sent the server responds with the actual page result. Now if you use WebRequest (or WebClient) the default behavior is to re-authenticate on every request that requires authorization. This means if you look in  Fiddler or some other HTTP client Proxy that captures requests you’ll see that each request re-authenticates: Here are two requests fired back to back: and you can see the 401 challenge, the 200 response for both requests. If you watch this same conversation between a browser and a server you’ll notice that the first 401 is also there but the subsequent 401 requests are not present. WebRequest.PreAuthenticate And this is precisely what the WebRequest.PreAuthenticate property does: It’s a caching mechanism that caches the connection credentials for a given domain in the active process and resends it on subsequent requests. It does not send credentials on the first request but it will cache credentials on subsequent requests after authentication has succeeded: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rick", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential("rstrahl", "secret", "rasnote"); req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested; req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); which results in the desired sequence: where only the first request doesn’t send credentials. This is quite useful as it saves quite a few round trips to the server – bascially it saves one auth request request for every authenticated request you make. In most scenarios I think you’d want to send these credentials this way but one downside to this is that there’s no way to log out the client. Since the client always sends the credentials once authenticated only an explicit operation ON THE SERVER can undo the credentials by forcing another login explicitly (ie. re-challenging with a forced 401 request). Forcing Basic Authentication Credentials on the first Request On a few occasions I’ve needed to send credentials on a first request – mainly to some oddball third party Web Services (why you’d want to use Basic Auth on a Web Service is beyond me – don’t ask but it’s not uncommon in my experience). This is true of certain services that are using Basic Authentication (especially some Apache based Web Services) and REQUIRE that the authentication is sent right from the first request. No challenge first. Ugly but there it is. Now the following works only with Basic Authentication because it’s pretty straight forward to create the Basic Authorization ‘token’ in code since it’s just an unencrypted encoding of the user name and password into base64. As you might guess this is totally unsecure and should only be used when using HTTPS/SSL connections (i’m not in this example so I can capture the Fiddler trace and my local machine doesn’t have a cert installed, but for production apps ALWAYS use SSL with basic auth). The idea is that you simply add the required Authorization header to the request on your own along with the authorization string that encodes the username and password: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "rick"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.AuthenticationLevel = System.Net.Security.AuthenticationLevel.MutualAuthRequested;req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); This works and causes the request to immediately send auth information to the server. However, this only works with Basic Auth because you can actually create the authentication credentials easily on the client because it’s essentially clear text. The same doesn’t work for Windows or Digest authentication since you can’t easily create the authentication token on the client and send it to the server. Another issue with this approach is that PreAuthenticate has no effect when you manually force the authentication. As far as Web Request is concerned it never sent the authentication information so it’s not actually caching the value any longer. If you run 3 requests in a row like this: string url = "http://rasnote/wconnect/admin/wc.wc?_maintain~ShowStatus"; HttpWebRequest req = HttpWebRequest.Create(url) as HttpWebRequest; string user = "ricks"; string pwd = "secret"; string domain = "www.west-wind.com"; string auth = "Basic " + Convert.ToBase64String(System.Text.Encoding.Default.GetBytes(user + ":" + pwd)); req.PreAuthenticate = true; req.Headers.Add("Authorization", auth); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; WebResponse resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); resp.Close(); req = HttpWebRequest.Create(url) as HttpWebRequest; req.PreAuthenticate = true; req.Credentials = new NetworkCredential(user, pwd, domain); req.UserAgent = ": Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.3) Gecko/20090824 Firefox/3.5.3 (.NET CLR 4.0.20506)"; resp = req.GetResponse(); you’ll find the trace looking like this: where the first request (the one we explicitly add the header to) authenticates, the second challenges, and any subsequent ones then use the PreAuthenticate credential caching. In effect you’ll end up with one extra 401 request in this scenario, which is still better than 401 challenges on each request. Getting Access to WebRequest in Classic .NET Web Service Clients If you’re running a classic .NET Web Service client (non-WCF) one issue with the above is how do you get access to the WebRequest to actually add the custom headers to do the custom Authentication described above? One easy way is to implement a partial class that allows you add headers with something like this: public partial class TaxService { protected NameValueCollection Headers = new NameValueCollection(); public void AddHttpHeader(string key, string value) { this.Headers.Add(key,value); } public void ClearHttpHeaders() { this.Headers.Clear(); } protected override WebRequest GetWebRequest(Uri uri) { HttpWebRequest request = (HttpWebRequest) base.GetWebRequest(uri); request.Headers.Add(this.Headers); return request; } } where TaxService is the name of the .NET generated proxy class. In code you can then call AddHttpHeader() anywhere to add additional headers which are sent as part of the GetWebRequest override. Nice and simple once you know where to hook it. For WCF there’s a bit more work involved by creating a message extension as described here: http://weblogs.asp.net/avnerk/archive/2006/04/26/Adding-custom-headers-to-every-WCF-call-_2D00_-a-solution.aspx. FWIW, I think that HTTP header manipulation should be readily available on any HTTP based Web Service client DIRECTLY without having to subclass or implement a special interface hook. But alas a little extra work is required in .NET to make this happen Not a Common Problem, but when it happens… This has been one of those issues that is really rare, but it’s bitten me on several occasions when dealing with oddball Web services – a couple of times in my own work interacting with various Web Services and a few times on customer projects that required interaction with credentials-first services. Since the servers determine the protocol, we don’t have a choice but to follow the protocol. Lovely following standards that implementers decide to ignore, isn’t it? :-}© Rick Strahl, West Wind Technologies, 2005-2010Posted in .NET  CSharp  Web Services  

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  • Checking for & storing multiple CheckBox selections in CSharp.

    - by Matt
    I'm very new to CSharp and I can't seem to find a good solution to what I would consider a simple problem. Basically I'm trying to determine which CheckBoxs have been selected by the user and then randomly generate combinations of the selections the user has made. As new as I am, I am aware that you can use a simple statement such as: checkBox1.IsChecked == true I could have a long set of if statements which update an array/collection, but I'm told that in Csharp there is a way of determining which CheckBoxs are checked by querying the GroupBox that the CheckBoxs are in. Unless I'm mistaken (which is very possible) this is achieved by using Control features, unfortunately I've not come across these yet in my learning so if someone could clear things up that would be great. In summation, if someone has a simple solution for running through a set of checkBoxs and storing only the selected ones I would be most grateful.

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  • Creating a dynamic, extensible C# Expando Object

    - by Rick Strahl
    I love dynamic functionality in a strongly typed language because it offers us the best of both worlds. In C# (or any of the main .NET languages) we now have the dynamic type that provides a host of dynamic features for the static C# language. One place where I've found dynamic to be incredibly useful is in building extensible types or types that expose traditionally non-object data (like dictionaries) in easier to use and more readable syntax. I wrote about a couple of these for accessing old school ADO.NET DataRows and DataReaders more easily for example. These classes are dynamic wrappers that provide easier syntax and auto-type conversions which greatly simplifies code clutter and increases clarity in existing code. ExpandoObject in .NET 4.0 Another great use case for dynamic objects is the ability to create extensible objects - objects that start out with a set of static members and then can add additional properties and even methods dynamically. The .NET 4.0 framework actually includes an ExpandoObject class which provides a very dynamic object that allows you to add properties and methods on the fly and then access them again. For example with ExpandoObject you can do stuff like this:dynamic expand = new ExpandoObject(); expand.Name = "Rick"; expand.HelloWorld = (Func<string, string>) ((string name) => { return "Hello " + name; }); Console.WriteLine(expand.Name); Console.WriteLine(expand.HelloWorld("Dufus")); Internally ExpandoObject uses a Dictionary like structure and interface to store properties and methods and then allows you to add and access properties and methods easily. As cool as ExpandoObject is it has a few shortcomings too: It's a sealed type so you can't use it as a base class It only works off 'properties' in the internal Dictionary - you can't expose existing type data It doesn't serialize to XML or with DataContractSerializer/DataContractJsonSerializer Expando - A truly extensible Object ExpandoObject is nice if you just need a dynamic container for a dictionary like structure. However, if you want to build an extensible object that starts out with a set of strongly typed properties and then allows you to extend it, ExpandoObject does not work because it's a sealed class that can't be inherited. I started thinking about this very scenario for one of my applications I'm building for a customer. In this system we are connecting to various different user stores. Each user store has the same basic requirements for username, password, name etc. But then each store also has a number of extended properties that is available to each application. In the real world scenario the data is loaded from the database in a data reader and the known properties are assigned from the known fields in the database. All unknown fields are then 'added' to the expando object dynamically. In the past I've done this very thing with a separate property - Properties - just like I do for this class. But the property and dictionary syntax is not ideal and tedious to work with. I started thinking about how to represent these extra property structures. One way certainly would be to add a Dictionary, or an ExpandoObject to hold all those extra properties. But wouldn't it be nice if the application could actually extend an existing object that looks something like this as you can with the Expando object:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } } and then simply start extending the properties of this object dynamically? Using the Expando object I describe later you can now do the following:[TestMethod] public void UserExampleTest() { var user = new User(); // Set strongly typed properties user.Email = "[email protected]"; user.Password = "nonya123"; user.Name = "Rickochet"; user.Active = true; // Now add dynamic properties dynamic duser = user; duser.Entered = DateTime.Now; duser.Accesses = 1; // you can also add dynamic props via indexer user["NickName"] = "AntiSocialX"; duser["WebSite"] = "http://www.west-wind.com/weblog"; // Access strong type through dynamic ref Assert.AreEqual(user.Name,duser.Name); // Access strong type through indexer Assert.AreEqual(user.Password,user["Password"]); // access dyanmically added value through indexer Assert.AreEqual(duser.Entered,user["Entered"]); // access index added value through dynamic Assert.AreEqual(user["NickName"],duser.NickName); // loop through all properties dynamic AND strong type properties (true) foreach (var prop in user.GetProperties(true)) { object val = prop.Value; if (val == null) val = "null"; Console.WriteLine(prop.Key + ": " + val.ToString()); } } As you can see this code somewhat blurs the line between a static and dynamic type. You start with a strongly typed object that has a fixed set of properties. You can then cast the object to dynamic (as I discussed in my last post) and add additional properties to the object. You can also use an indexer to add dynamic properties to the object. To access the strongly typed properties you can use either the strongly typed instance, the indexer or the dynamic cast of the object. Personally I think it's kinda cool to have an easy way to access strongly typed properties by string which can make some data scenarios much easier. To access the 'dynamically added' properties you can use either the indexer on the strongly typed object, or property syntax on the dynamic cast. Using the dynamic type allows all three modes to work on both strongly typed and dynamic properties. Finally you can iterate over all properties, both dynamic and strongly typed if you chose. Lots of flexibility. Note also that by default the Expando object works against the (this) instance meaning it extends the current object. You can also pass in a separate instance to the constructor in which case that object will be used to iterate over to find properties rather than this. Using this approach provides some really interesting functionality when use the dynamic type. To use this we have to add an explicit constructor to the Expando subclass:public class User : Westwind.Utilities.Dynamic.Expando { public string Email { get; set; } public string Password { get; set; } public string Name { get; set; } public bool Active { get; set; } public DateTime? ExpiresOn { get; set; } public User() : base() { } // only required if you want to mix in seperate instance public User(object instance) : base(instance) { } } to allow the instance to be passed. When you do you can now do:[TestMethod] public void ExpandoMixinTest() { // have Expando work on Addresses var user = new User( new Address() ); // cast to dynamicAccessToPropertyTest dynamic duser = user; // Set strongly typed properties duser.Email = "[email protected]"; user.Password = "nonya123"; // Set properties on address object duser.Address = "32 Kaiea"; //duser.Phone = "808-123-2131"; // set dynamic properties duser.NonExistantProperty = "This works too"; // shows default value Address.Phone value Console.WriteLine(duser.Phone); } Using the dynamic cast in this case allows you to access *three* different 'objects': The strong type properties, the dynamically added properties in the dictionary and the properties of the instance passed in! Effectively this gives you a way to simulate multiple inheritance (which is scary - so be very careful with this, but you can do it). How Expando works Behind the scenes Expando is a DynamicObject subclass as I discussed in my last post. By implementing a few of DynamicObject's methods you can basically create a type that can trap 'property missing' and 'method missing' operations. When you access a non-existant property a known method is fired that our code can intercept and provide a value for. Internally Expando uses a custom dictionary implementation to hold the dynamic properties you might add to your expandable object. Let's look at code first. The code for the Expando type is straight forward and given what it provides relatively short. Here it is.using System; using System.Collections.Generic; using System.Linq; using System.Dynamic; using System.Reflection; namespace Westwind.Utilities.Dynamic { /// <summary> /// Class that provides extensible properties and methods. This /// dynamic object stores 'extra' properties in a dictionary or /// checks the actual properties of the instance. /// /// This means you can subclass this expando and retrieve either /// native properties or properties from values in the dictionary. /// /// This type allows you three ways to access its properties: /// /// Directly: any explicitly declared properties are accessible /// Dynamic: dynamic cast allows access to dictionary and native properties/methods /// Dictionary: Any of the extended properties are accessible via IDictionary interface /// </summary> [Serializable] public class Expando : DynamicObject, IDynamicMetaObjectProvider { /// <summary> /// Instance of object passed in /// </summary> object Instance; /// <summary> /// Cached type of the instance /// </summary> Type InstanceType; PropertyInfo[] InstancePropertyInfo { get { if (_InstancePropertyInfo == null && Instance != null) _InstancePropertyInfo = Instance.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.DeclaredOnly); return _InstancePropertyInfo; } } PropertyInfo[] _InstancePropertyInfo; /// <summary> /// String Dictionary that contains the extra dynamic values /// stored on this object/instance /// </summary> /// <remarks>Using PropertyBag to support XML Serialization of the dictionary</remarks> public PropertyBag Properties = new PropertyBag(); //public Dictionary<string,object> Properties = new Dictionary<string, object>(); /// <summary> /// This constructor just works off the internal dictionary and any /// public properties of this object. /// /// Note you can subclass Expando. /// </summary> public Expando() { Initialize(this); } /// <summary> /// Allows passing in an existing instance variable to 'extend'. /// </summary> /// <remarks> /// You can pass in null here if you don't want to /// check native properties and only check the Dictionary! /// </remarks> /// <param name="instance"></param> public Expando(object instance) { Initialize(instance); } protected virtual void Initialize(object instance) { Instance = instance; if (instance != null) InstanceType = instance.GetType(); } /// <summary> /// Try to retrieve a member by name first from instance properties /// followed by the collection entries. /// </summary> /// <param name="binder"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryGetMember(GetMemberBinder binder, out object result) { result = null; // first check the Properties collection for member if (Properties.Keys.Contains(binder.Name)) { result = Properties[binder.Name]; return true; } // Next check for Public properties via Reflection if (Instance != null) { try { return GetProperty(Instance, binder.Name, out result); } catch { } } // failed to retrieve a property result = null; return false; } /// <summary> /// Property setter implementation tries to retrieve value from instance /// first then into this object /// </summary> /// <param name="binder"></param> /// <param name="value"></param> /// <returns></returns> public override bool TrySetMember(SetMemberBinder binder, object value) { // first check to see if there's a native property to set if (Instance != null) { try { bool result = SetProperty(Instance, binder.Name, value); if (result) return true; } catch { } } // no match - set or add to dictionary Properties[binder.Name] = value; return true; } /// <summary> /// Dynamic invocation method. Currently allows only for Reflection based /// operation (no ability to add methods dynamically). /// </summary> /// <param name="binder"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { if (Instance != null) { try { // check instance passed in for methods to invoke if (InvokeMethod(Instance, binder.Name, args, out result)) return true; } catch { } } result = null; return false; } /// <summary> /// Reflection Helper method to retrieve a property /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="result"></param> /// <returns></returns> protected bool GetProperty(object instance, string name, out object result) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.GetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { result = ((PropertyInfo)mi).GetValue(instance,null); return true; } } result = null; return false; } /// <summary> /// Reflection helper method to set a property value /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="value"></param> /// <returns></returns> protected bool SetProperty(object instance, string name, object value) { if (instance == null) instance = this; var miArray = InstanceType.GetMember(name, BindingFlags.Public | BindingFlags.SetProperty | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0]; if (mi.MemberType == MemberTypes.Property) { ((PropertyInfo)mi).SetValue(Instance, value, null); return true; } } return false; } /// <summary> /// Reflection helper method to invoke a method /// </summary> /// <param name="instance"></param> /// <param name="name"></param> /// <param name="args"></param> /// <param name="result"></param> /// <returns></returns> protected bool InvokeMethod(object instance, string name, object[] args, out object result) { if (instance == null) instance = this; // Look at the instanceType var miArray = InstanceType.GetMember(name, BindingFlags.InvokeMethod | BindingFlags.Public | BindingFlags.Instance); if (miArray != null && miArray.Length > 0) { var mi = miArray[0] as MethodInfo; result = mi.Invoke(Instance, args); return true; } result = null; return false; } /// <summary> /// Convenience method that provides a string Indexer /// to the Properties collection AND the strongly typed /// properties of the object by name. /// /// // dynamic /// exp["Address"] = "112 nowhere lane"; /// // strong /// var name = exp["StronglyTypedProperty"] as string; /// </summary> /// <remarks> /// The getter checks the Properties dictionary first /// then looks in PropertyInfo for properties. /// The setter checks the instance properties before /// checking the Properties dictionary. /// </remarks> /// <param name="key"></param> /// /// <returns></returns> public object this[string key] { get { try { // try to get from properties collection first return Properties[key]; } catch (KeyNotFoundException ex) { // try reflection on instanceType object result = null; if (GetProperty(Instance, key, out result)) return result; // nope doesn't exist throw; } } set { if (Properties.ContainsKey(key)) { Properties[key] = value; return; } // check instance for existance of type first var miArray = InstanceType.GetMember(key, BindingFlags.Public | BindingFlags.GetProperty); if (miArray != null && miArray.Length > 0) SetProperty(Instance, key, value); else Properties[key] = value; } } /// <summary> /// Returns and the properties of /// </summary> /// <param name="includeProperties"></param> /// <returns></returns> public IEnumerable<KeyValuePair<string,object>> GetProperties(bool includeInstanceProperties = false) { if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) yield return new KeyValuePair<string, object>(prop.Name, prop.GetValue(Instance, null)); } foreach (var key in this.Properties.Keys) yield return new KeyValuePair<string, object>(key, this.Properties[key]); } /// <summary> /// Checks whether a property exists in the Property collection /// or as a property on the instance /// </summary> /// <param name="item"></param> /// <returns></returns> public bool Contains(KeyValuePair<string, object> item, bool includeInstanceProperties = false) { bool res = Properties.ContainsKey(item.Key); if (res) return true; if (includeInstanceProperties && Instance != null) { foreach (var prop in this.InstancePropertyInfo) { if (prop.Name == item.Key) return true; } } return false; } } } Although the Expando class supports an indexer, it doesn't actually implement IDictionary or even IEnumerable. It only provides the indexer and Contains() and GetProperties() methods, that work against the Properties dictionary AND the internal instance. The reason for not implementing IDictionary is that a) it doesn't add much value since you can access the Properties dictionary directly and that b) I wanted to keep the interface to class very lean so that it can serve as an entity type if desired. Implementing these IDictionary (or even IEnumerable) causes LINQ extension methods to pop up on the type which obscures the property interface and would only confuse the purpose of the type. IDictionary and IEnumerable are also problematic for XML and JSON Serialization - the XML Serializer doesn't serialize IDictionary<string,object>, nor does the DataContractSerializer. The JavaScriptSerializer does serialize, but it treats the entire object like a dictionary and doesn't serialize the strongly typed properties of the type, only the dictionary values which is also not desirable. Hence the decision to stick with only implementing the indexer to support the user["CustomProperty"] functionality and leaving iteration functions to the publicly exposed Properties dictionary. Note that the Dictionary used here is a custom PropertyBag class I created to allow for serialization to work. One important aspect for my apps is that whatever custom properties get added they have to be accessible to AJAX clients since the particular app I'm working on is a SIngle Page Web app where most of the Web access is through JSON AJAX calls. PropertyBag can serialize to XML and one way serialize to JSON using the JavaScript serializer (not the DCS serializers though). The key components that make Expando work in this code are the Properties Dictionary and the TryGetMember() and TrySetMember() methods. The Properties collection is public so if you choose you can explicitly access the collection to get better performance or to manipulate the members in internal code (like loading up dynamic values form a database). Notice that TryGetMember() and TrySetMember() both work against the dictionary AND the internal instance to retrieve and set properties. This means that user["Name"] works against native properties of the object as does user["Name"] = "RogaDugDog". What's your Use Case? This is still an early prototype but I've plugged it into one of my customer's applications and so far it's working very well. The key features for me were the ability to easily extend the type with values coming from a database and exposing those values in a nice and easy to use manner. I'm also finding that using this type of object for ViewModels works very well to add custom properties to view models. I suspect there will be lots of uses for this - I've been using the extra dictionary approach to extensibility for years - using a dynamic type to make the syntax cleaner is just a bonus here. What can you think of to use this for? Resources Source Code and Tests (GitHub) Also integrated in Westwind.Utilities of the West Wind Web Toolkit West Wind Utilities NuGet© Rick Strahl, West Wind Technologies, 2005-2012Posted in CSharp  .NET  Dynamic Types   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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