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  • Why does Visual Studio's "Unused References..." button not flag System.Xml and System.Xml.Linq?

    - by mcjabberz
    I was trying to finish up a VB.NET class library project when I tried to remove all unused references. I know for a fact that I'm not explicitly using any thing from the System.Xml and System.Xml.Linq assemblies yet the "Unused References..." button never flags them for removal. In fact I even tried "Unused References..." on a blank project and it still never flagged them. The only reason I could think of is that either mscorlib.dll or System.dll is using System.Xml.dll or System.Xml.Linq.dll. Are they safe to remove?

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  • Using T4 to generate Configuration classes

    - by Justin Hoffman
    I wanted to try to use T4 to read a web.config and generate all of the appSettings and connectionStrings as properties of a class.  I elected in this template only to output appSettings and connectionStrings but you can see it would be easily adapted for app specific settings, bindings etc.  This allows for quick access to config values as well as removing the potential for typo's when accessing values from the ConfigurationManager. One caveat: a developer would need to remember to run the .tt file after adding an entry to the web.config.  However, one would quickly notice when trying to access the property from the generated class (it wouldn't be there).  Additionally, there are other options as noted here. The first step was to create the .tt file.  Note that this is a basic example, it could be extended even further I'm sure.  In this example I just manually input the path to the web.config file. <#@ template debug="false" hostspecific="true" language="C#" #><#@ output extension=".cs" #><#@ assembly Name="System.Configuration" #><#@ assembly name="System.Xml" #><#@ assembly name="System.Xml.Linq" #><#@ assembly name="System.Net" #><#@ assembly name="System" #><#@ import namespace="System.Configuration" #><#@ import namespace="System.Xml" #><#@ import namespace="System.Net" #><#@ import namespace="Microsoft.VisualStudio.TextTemplating" #><#@ import namespace="System.Xml.Linq" #>using System;using System.Configuration;using System.Xml;using System.Xml.Linq;using System.Linq;namespace MyProject.Web { public partial class Configurator { <# var xDocument = XDocument.Load(@"G:\MySolution\MyProject\Web.config"); var results = xDocument.Descendants("appSettings"); const string key = "key"; const string name = "name"; foreach (var xElement in results.Descendants()) {#> public string <#= xElement.Attribute(key).Value#>{get {return ConfigurationManager.AppSettings[<#= string.Format("{0}{1}{2}","\"" , xElement.Attribute(key).Value, "\"")#>];}} <#}#> <# var connectionStrings = xDocument.Descendants("connectionStrings"); foreach(var connString in connectionStrings.Descendants()) {#> public string <#= connString.Attribute(name).Value#>{get {return ConfigurationManager.ConnectionStrings[<#= string.Format("{0}{1}{2}","\"" , connString.Attribute(name).Value, "\"")#>].ConnectionString;}} <#} #> }} The resulting .cs file: using System;using System.Configuration;using System.Xml;using System.Xml.Linq;using System.Linq;namespace MyProject.Web { public partial class Configurator { public string ClientValidationEnabled{get {return ConfigurationManager.AppSettings["ClientValidationEnabled"];}} public string UnobtrusiveJavaScriptEnabled{get {return ConfigurationManager.AppSettings["UnobtrusiveJavaScriptEnabled"];}} public string ServiceUri{get {return ConfigurationManager.AppSettings["ServiceUri"];}} public string TestConnection{get {return ConfigurationManager.ConnectionStrings["TestConnection"].ConnectionString;}} public string SecondTestConnection{get {return ConfigurationManager.ConnectionStrings["SecondTestConnection"].ConnectionString;}} }} Next, I extended the partial class for easy access to the Configuration. However, you could just use the generated class file itself. using System;using System.Linq;using System.Xml.Linq;namespace MyProject.Web{ public partial class Configurator { private static readonly Configurator Instance = new Configurator(); public static Configurator For { get { return Instance; } } }} Finally, in my example, I used the Configurator class like so: [TestMethod] public void Test_Web_Config() { var result = Configurator.For.ServiceUri; Assert.AreEqual(result, "http://localhost:30237/Service1/"); }

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  • SOLVED: The type or namespace name 'Linq' does not exist in the namespace 'System' - are you missing

    This problem has been cropping up a lot recently - projects will complain of missing namespace's when I open them up and attempt to compile the first time. If this has happened to you then read on for a simple fix. Scenario I don't know if this one is a bug in Visual Studio 2010 (Beta 2 and RC1) or something else but recently I have noticed this error cropping up more and more. When I open an existing project it might fail to compile. I have also noticed it happen when I have downloaded a fresh...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Parallelism in .NET – Part 8, PLINQ’s ForAll Method

    - by Reed
    Parallel LINQ extends LINQ to Objects, and is typically very similar.  However, as I previously discussed, there are some differences.  Although the standard way to handle simple Data Parellelism is via Parallel.ForEach, it’s possible to do the same thing via PLINQ. PLINQ adds a new method unavailable in standard LINQ which provides new functionality… LINQ is designed to provide a much simpler way of handling querying, including filtering, ordering, grouping, and many other benefits.  Reading the description in LINQ to Objects on MSDN, it becomes clear that the thinking behind LINQ deals with retrieval of data.  LINQ works by adding a functional programming style on top of .NET, allowing us to express filters in terms of predicate functions, for example. PLINQ is, generally, very similar.  Typically, when using PLINQ, we write declarative statements to filter a dataset or perform an aggregation.  However, PLINQ adds one new method, which provides a very different purpose: ForAll. The ForAll method is defined on ParallelEnumerable, and will work upon any ParallelQuery<T>.  Unlike the sequence operators in LINQ and PLINQ, ForAll is intended to cause side effects.  It does not filter a collection, but rather invokes an action on each element of the collection. At first glance, this seems like a bad idea.  For example, Eric Lippert clearly explained two philosophical objections to providing an IEnumerable<T>.ForEach extension method, one of which still applies when parallelized.  The sole purpose of this method is to cause side effects, and as such, I agree that the ForAll method “violates the functional programming principles that all the other sequence operators are based upon”, in exactly the same manner an IEnumerable<T>.ForEach extension method would violate these principles.  Eric Lippert’s second reason for disliking a ForEach extension method does not necessarily apply to ForAll – replacing ForAll with a call to Parallel.ForEach has the same closure semantics, so there is no loss there. Although ForAll may have philosophical issues, there is a pragmatic reason to include this method.  Without ForAll, we would take a fairly serious performance hit in many situations.  Often, we need to perform some filtering or grouping, then perform an action using the results of our filter.  Using a standard foreach statement to perform our action would avoid this philosophical issue: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action foreach (var item in filteredItems) { // These will now run serially item.DoSomething(); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } This would cause a loss in performance, since we lose any parallelism in place, and cause all of our actions to be run serially. We could easily use a Parallel.ForEach instead, which adds parallelism to the actions: // Filter our collection var filteredItems = collection.AsParallel().Where( i => i.SomePredicate() ); // Now perform an action once the filter completes Parallel.ForEach(filteredItems, item => { // These will now run in parallel item.DoSomething(); }); This is a noticeable improvement, since both our filtering and our actions run parallelized.  However, there is still a large bottleneck in place here.  The problem lies with my comment “perform an action once the filter completes”.  Here, we’re parallelizing the filter, then collecting all of the results, blocking until the filter completes.  Once the filtering of every element is completed, we then repartition the results of the filter, reschedule into multiple threads, and perform the action on each element.  By moving this into two separate statements, we potentially double our parallelization overhead, since we’re forcing the work to be partitioned and scheduled twice as many times. This is where the pragmatism comes into play.  By violating our functional principles, we gain the ability to avoid the overhead and cost of rescheduling the work: // Perform an action on the results of our filter collection .AsParallel() .Where( i => i.SomePredicate() ) .ForAll( i => i.DoSomething() ); The ability to avoid the scheduling overhead is a compelling reason to use ForAll.  This really goes back to one of the key points I discussed in data parallelism: Partition your problem in a way to place the most work possible into each task.  Here, this means leaving the statement attached to the expression, even though it causes side effects and is not standard usage for LINQ. This leads to my one guideline for using ForAll: The ForAll extension method should only be used to process the results of a parallel query, as returned by a PLINQ expression. Any other usage scenario should use Parallel.ForEach, instead.

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  • Telerik Releases a new Visual Entity Designer

    Love LINQ to SQL but are concerned that it is a second class citizen? Need to connect to more databases other than SQL Server? Think that the Entity Framework is too complex? Want a domain model designer for data access that is easy, yet powerful? Then the Telerik Visual Entity Designer is for you. Built on top of Telerik OpenAccess ORM, a very mature and robust product, Teleriks Visual Entity Designer is a new way to build your domain model that is very powerful and also real easy to use. How easy? Ill show you here. First Look: Using the Telerik Visual Entity Designer To get started, you need to install the Telerik OpenAccess ORM Q1 release for Visual Studio 2008 or 2010. You dont need to use any of the Telerik OpenAccess wizards, designers, or using statements. Just right click on your project and select Add|New Item from the context menu. Choose Telerik OpenAccess Domain Model from the Visual Studio project templates. (Note to existing OpenAccess users, dont run the Enable ORM wizard or any other OpenAccess menu unless you are building OpenAccess Entities.) You will then have to specify the database backend (SQL Server, SQL Azure, Oracle, MySQL, etc) and connection. After you establish your connection, select the database objects you want to add to your domain model. You can also name your model, by default it will be NameofyourdatabaseEntityDiagrams. You can click finish here if you are comfortable, or tweak some advanced settings. Many users of domain models like to add prefixes and suffixes to classes, fields, and properties as well as handle pluralization. I personally accept the defaults, however, I hate how DBAs force underscores on me, so I click on the option to remove them. You can also tweak your namespace, mapping options, and define your own code generation template to gain further control over the outputted code. This is a very powerful feature, but for now, I will just accept the defaults.   When we click finish, you can see your domain model as a file with the .rlinq extension in the Solution Explorer. You can also bring up the visual designer to view or further tweak your model by double clicking on the model in the Solution Explorer.  Time to use the model! Writing a LINQ Query Programming against the domain model is very simple using LINQ. Just set a reference to the model (line 12 of the code below) and write a standard LINQ statement (lines 14-16).  (OpenAccess users: notice the you dont need any using statements for OpenAccess or an IObjectScope, just raw LINQ against your model.) 1: using System; 2: using System.Linq; 3: //no need for anOpenAccess using statement 4:   5: namespace ConsoleApplication3 6: { 7: class Program 8: { 9: static void Main(string[] args) 10: { 11: //a reference tothe data context 12: NorthwindEntityDiagrams dat = new NorthwindEntityDiagrams(); 13: //LINQ Statement 14: var result = from c in dat.Customers 15: where c.Country == "Germany" 16: select c; 17:   18: //Print out the company name 19: foreach (var cust in result) 20: { 21: Console.WriteLine("CompanyName: " + cust.CompanyName); 22: } 23: //keep the consolewindow open 24: Console.Read(); 25: } 26: } 27: } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Lines 19-24 loop through the result of our LINQ query and displays the results. Thats it! All of the super powerful features of OpenAccess are available to you to further enhance your experience, however, in most cases this is all you need. In future posts I will show how to use the Visual Designer with some other scenarios. Stay tuned. Enjoy! Technorati Tags: Telerik,OpenAccess,LINQ Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Can a class inherit from LambdaExpression in .NET? Or is this not recommended?

    - by d.
    Consider the following code (C# 4.0): public class Foo : LambdaExpression { } This throws the following design-time error: Foo does not implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) There's absolutely no problem with public class Foo : Expression { } but, out of curiosity and for the sake of learning, I've searched in Google System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) and guess what: zero results returned (when was the last time you saw that?). Needless to say, I haven't found any documentation on this method anywhere else. As I said, one can easily inherit from Expression; on the other hand LambdaExpression, while not marked as sealed (Expression<TDelegate> inherits from it), seems to be designed to prevent inheriting from it. Is this actually the case? Does anyone out there know what this method is about? EDIT (1): More info based on the first answers - If you try to implement Accept, the editor (C# 2010 Express) automatically gives you the following stub: protected override Expression Accept(System.Linq.Expressions.ExpressionVisitor visitor) { return base.Accept(visitor); } But you still get the same error. If you try to use a parameter of type StackSpiller directly, the compiler throws a different error: System.Linq.Expressions.Compiler.StackSpiller is inaccessible due to its protection level. EDIT (2): Based on other answers, inheriting from LambdaExpression is not possible so the question as to whether or not it is recommended becomes irrelevant. I wonder if, in cases like this, the error message should be Foo cannot implement inherited abstract member System.Linq.Expressions.LambdaExpression.Accept(System.Linq.Expressions.Compiler.StackSpiller) because [reasons go here]; the current error message (as some answers prove) seems to tell me that all I need to do is implement Accept (which I can't do).

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  • SSIS - XML Source Script

    - by simonsabin
    The XML Source in SSIS is great if you have a 1 to 1 mapping between entity and table. You can do more complex mapping but it becomes very messy and won't perform. What other options do you have? The challenge with XML processing is to not need a huge amount of memory. I remember using the early versions of Biztalk with loaded the whole document into memory to map from one document type to another. This was fine for small documents but was an absolute killer for large documents. You therefore need a streaming approach. For flexibility however you want to be able to generate your rows easily, and if you've ever used the XmlReader you will know its ugly code to write. That brings me on to LINQ. The is an implementation of LINQ over XML which is really nice. You can write nice LINQ queries instead of the XMLReader stuff. The downside is that by default LINQ to XML requires a whole XML document to work with. No streaming. Your code would look like this. We create an XDocument and then enumerate over a set of annoymous types we generate from our LINQ statement XDocument x = XDocument.Load("C:\\TEMP\\CustomerOrders-Attribute.xml");   foreach (var xdata in (from customer in x.Elements("OrderInterface").Elements("Customer")                        from order in customer.Elements("Orders").Elements("Order")                        select new { Account = customer.Attribute("AccountNumber").Value                                   , OrderDate = order.Attribute("OrderDate").Value }                        )) {     Output0Buffer.AddRow();     Output0Buffer.AccountNumber = xdata.Account;     Output0Buffer.OrderDate = Convert.ToDateTime(xdata.OrderDate); } As I said the downside to this is that you are loading the whole document into memory. I did some googling and came across some helpful videos from a nice UK DPE Mike Taulty http://www.microsoft.com/uk/msdn/screencasts/screencast/289/LINQ-to-XML-Streaming-In-Large-Documents.aspx. Which show you how you can combine LINQ and the XmlReader to get a semi streaming approach. I took what he did and implemented it in SSIS. What I found odd was that when I ran it I got different numbers between using the streamed and non streamed versions. I found the cause was a little bug in Mikes code that causes the pointer in the XmlReader to progress past the start of the element and thus foreach (var xdata in (from customer in StreamReader("C:\\TEMP\\CustomerOrders-Attribute.xml","Customer")                                from order in customer.Elements("Orders").Elements("Order")                                select new { Account = customer.Attribute("AccountNumber").Value                                           , OrderDate = order.Attribute("OrderDate").Value }                                ))         {             Output0Buffer.AddRow();             Output0Buffer.AccountNumber = xdata.Account;             Output0Buffer.OrderDate = Convert.ToDateTime(xdata.OrderDate);         } These look very similiar and they are the key element is the method we are calling, StreamReader. This method is what gives us streaming, what it does is return a enumerable list of elements, because of the way that LINQ works this results in the data being streamed in. static IEnumerable<XElement> StreamReader(String filename, string elementName) {     using (XmlReader xr = XmlReader.Create(filename))     {         xr.MoveToContent();         while (xr.Read()) //Reads the first element         {             while (xr.NodeType == XmlNodeType.Element && xr.Name == elementName)             {                 XElement node = (XElement)XElement.ReadFrom(xr);                   yield return node;             }         }         xr.Close();     } } This code is specifically designed to return a list of the elements with a specific name. The first Read reads the root element and then the inner while loop checks to see if the current element is the type we want. If not we do the xr.Read() again until we find the element type we want. We then use the neat function XElement.ReadFrom to read an element and all its sub elements into an XElement. This is what is returned and can be consumed by the LINQ statement. Essentially once one element has been read we need to check if we are still on the same element type and name (the inner loop) This was Mikes mistake, if we called .Read again we would advance the XmlReader beyond the start of the Element and so the ReadFrom method wouldn't work. So with the code above you can use what ever LINQ statement you like to flatten your XML into the rowsets you want. You could even have multiple outputs and generate your own surrogate keys.        

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  • How can I extend a LINQ-to-SQL class without having to make changes every time the code is generated

    - by csharpnoob
    Hi, Update from comment: I need to extend linq-to-sql classes by own parameters and dont want to touch any generated classes. Any better suggestes are welcome. But I also don't want to do all attributes assignments all time again if the linq-to-sql classes are changing. so if vstudio generates new attribute to a class i have my own extended attributes kept separate, and the new innerited from the class itself Original question: i'm not sure if it's possible. I have a class car and a class mycar extended from class car. Class mycar has also a string list. Only difference. How can i cast now any car object to a mycar object without assigning all attributes each by hand. Like: Car car = new Car(); MyCar mcar = (MyCar) car; or MyCar mcar = new MyCar(car); or however i can extend car with own variables and don't have to do always Car car = new Car(); MyCar mcar = new MyCar(); mcar.name = car.name; mcar.xyz = car.xyz; ... Thanks.

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  • How to write linq query in Entity FrameWork but my table includes Foreignkey?

    - by programmerist
    i have a table it includes 3 foreignkey field like that: My Table: Kartlar ID (Pkey) RehberID (Fkey) KampanyaID (Fkey) BrimID (Fkey) Name Detail How can i write entity query with linq :? select * from Kartlar where RehberID=123 and KampanyaID=345 and BrimID=567 BUT please be carefull i can not see RehberID ,KampanyaID, BrimID in Entity they are Foreign Key. I should use Entity Key but How?

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  • Entity Framework v1 &ndash; tips and Tricks Part 3

    - by Rohit Gupta
    General Tips on Entity Framework v1 & Linq to Entities: ToTraceString() If you need to know the underlying SQL that the EF generates for a Linq To Entities query, then use the ToTraceString() method of the ObjectQuery class. (or use LINQPAD) Note that you need to cast the LINQToEntities query to ObjectQuery before calling TotraceString() as follows: 1: string efSQL = ((ObjectQuery)from c in ctx.Contact 2: where c.Address.Any(a => a.CountryRegion == "US") 3: select c.ContactID).ToTraceString(); ================================================================================ MARS or MultipleActiveResultSet When you create a EDM Model (EDMX file) from the database using Visual Studio, it generates a connection string with the same name as the name of the EntityContainer in CSDL. In the ConnectionString so generated it sets the MultipleActiveResultSet attribute to true by default. So if you are running the following query then it streams multiple readers over the same connection: 1: using (BAEntities context = new BAEntities()) 2: { 3: var cons = 4: from con in context.Contacts 5: where con.FirstName == "Jose" 6: select con; 7: foreach (var c in cons) 8: { 9: if (c.AddDate < new System.DateTime(2007, 1, 1)) 10: { 11: c.Addresses.Load(); 12: } 13: } 14: } ================================================================================= Explicitly opening and closing EntityConnection When you call ToList() or foreach on a LINQToEntities query the EF automatically closes the connection after all the records from the query have been consumed. Thus if you need to run many LINQToEntities queries over the same connection then explicitly open and close the connection as follows: 1: using (BAEntities context = new BAEntities()) 2: { 3: context.Connection.Open(); 4: var cons = from con in context.Contacts where con.FirstName == "Jose" 5: select con; 6: var conList = cons.ToList(); 7: var allCustomers = from con in context.Contacts.OfType<Customer>() 8: select con; 9: var allcustList = allCustomers.ToList(); 10: context.Connection.Close(); 11: } ====================================================================== Dispose ObjectContext only if required After you retrieve entities using the ObjectContext and you are not explicitly disposing the ObjectContext then insure that your code does consume all the records from the LinqToEntities query by calling .ToList() or foreach statement, otherwise the the database connection will remain open and will be closed by the garbage collector when it gets to dispose the ObjectContext. Secondly if you are making updates to the entities retrieved using LinqToEntities then insure that you dont inadverdently dispose of the ObjectContext after the entities are retrieved and before calling .SaveChanges() since you need the SAME ObjectContext to keep track of changes made to the Entities (by using ObjectStateEntry objects). So if you do need to explicitly dispose of the ObjectContext do so only after calling SaveChanges() and only if you dont need to change track the entities retrieved any further. ======================================================================= SQL InjectionAttacks under control with EFv1 LinqToEntities and LinqToSQL queries are parameterized before they are sent to the DB hence they are not vulnerable to SQL Injection attacks. EntitySQL may be slightly vulnerable to attacks since it does not use parameterized queries. However since the EntitySQL demands that the query be valid Entity SQL syntax and valid native SQL syntax at the same time. So the only way one can do a SQLInjection Attack is by knowing the SSDL of the EDM Model and be able to write the correct EntitySQL (note one cannot append regular SQL since then the query wont be a valid EntitySQL syntax) and append it to a parameter. ====================================================================== Improving Performance You can convert the EntitySets and AssociationSets in a EDM Model into precompiled Views using the edmgen utility. for e.g. the Customer Entity can be converted into a precompiled view using edmgen and all LinqToEntities query against the contaxt.Customer EntitySet will use the precompiled View instead of the EntitySet itself (the same being true for relationships (EntityReference & EntityCollections of a Entity)). The advantage being that when using precompiled views the performance will be much better. The syntax for generating precompiled views for a existing EF project is : edmgen /mode:ViewGeneration /inssdl:BAModel.ssdl /incsdl:BAModel.csdl /inmsl:BAModel.msl /p:Chap14.csproj Note that this will only generate precompiled views for EntitySets and Associations and not for existing LinqToEntities queries in the project.(for that use CompiledQuery.Compile<>) Secondly if you have a LinqToEntities query that you need to run multiple times, then one should precompile the query using CompiledQuery.Compile method. The CompiledQuery.Compile<> method accepts a lamda expression as a parameter, which denotes the LinqToEntities query  that you need to precompile. The following is a example of a lamda that we can pass into the CompiledQuery.Compile() method 1: Expression<Func<BAEntities, string, IQueryable<Customer>>> expr = (BAEntities ctx1, string loc) => 2: from c in ctx1.Contacts.OfType<Customer>() 3: where c.Reservations.Any(r => r.Trip.Destination.DestinationName == loc) 4: select c; Then we call the Compile Query as follows: 1: var query = CompiledQuery.Compile<BAEntities, string, IQueryable<Customer>>(expr); 2:  3: using (BAEntities ctx = new BAEntities()) 4: { 5: var loc = "Malta"; 6: IQueryable<Customer> custs = query.Invoke(ctx, loc); 7: var custlist = custs.ToList(); 8: foreach (var item in custlist) 9: { 10: Console.WriteLine(item.FullName); 11: } 12: } Note that if you created a ObjectQuery or a Enitity SQL query instead of the LINQToEntities query, you dont need precompilation for e.g. 1: An Example of EntitySQL query : 2: string esql = "SELECT VALUE c from Contacts AS c where c is of(BAGA.Customer) and c.LastName = 'Gupta'"; 3: ObjectQuery<Customer> custs = CreateQuery<Customer>(esql); 1: An Example of ObjectQuery built using ObjectBuilder methods: 2: from c in Contacts.OfType<Customer>().Where("it.LastName == 'Gupta'") 3: select c This is since the Query plan is cached and thus the performance improves a bit, however since the ObjectQuery or EntitySQL query still needs to materialize the results into Entities hence it will take the same amount of performance hit as with LinqToEntities. However note that not ALL EntitySQL based or QueryBuilder based ObjectQuery plans are cached. So if you are in doubt always create a LinqToEntities compiled query and use that instead ============================================================ GetObjectStateEntry Versus GetObjectByKey We can get to the Entity being referenced by the ObjectStateEntry via its Entity property and there are helper methods in the ObjectStateManager (osm.TryGetObjectStateEntry) to get the ObjectStateEntry for a entity (for which we know the EntityKey). Similarly The ObjectContext has helper methods to get an Entity i.e. TryGetObjectByKey(). TryGetObjectByKey() uses GetObjectStateEntry method under the covers to find the object, however One important difference between these 2 methods is that TryGetObjectByKey queries the database if it is unable to find the object in the context, whereas TryGetObjectStateEntry only looks in the context for existing entries. It will not make a trip to the database ============================================================= POCO objects with EFv1: To create POCO objects that can be used with EFv1. We need to implement 3 key interfaces: IEntityWithKey IEntityWithRelationships IEntityWithChangeTracker Implementing IEntityWithKey is not mandatory, but if you dont then we need to explicitly provide values for the EntityKey for various functions (for e.g. the functions needed to implement IEntityWithChangeTracker and IEntityWithRelationships). Implementation of IEntityWithKey involves exposing a property named EntityKey which returns a EntityKey object. Implementation of IEntityWithChangeTracker involves implementing a method named SetChangeTracker since there can be multiple changetrackers (Object Contexts) existing in memory at the same time. 1: public void SetChangeTracker(IEntityChangeTracker changeTracker) 2: { 3: _changeTracker = changeTracker; 4: } Additionally each property in the POCO object needs to notify the changetracker (objContext) that it is updating itself by calling the EntityMemberChanged and EntityMemberChanging methods on the changeTracker. for e.g.: 1: public EntityKey EntityKey 2: { 3: get { return _entityKey; } 4: set 5: { 6: if (_changeTracker != null) 7: { 8: _changeTracker.EntityMemberChanging("EntityKey"); 9: _entityKey = value; 10: _changeTracker.EntityMemberChanged("EntityKey"); 11: } 12: else 13: _entityKey = value; 14: } 15: } 16: ===================== Custom Property ==================================== 17:  18: [EdmScalarPropertyAttribute(IsNullable = false)] 19: public System.DateTime OrderDate 20: { 21: get { return _orderDate; } 22: set 23: { 24: if (_changeTracker != null) 25: { 26: _changeTracker.EntityMemberChanging("OrderDate"); 27: _orderDate = value; 28: _changeTracker.EntityMemberChanged("OrderDate"); 29: } 30: else 31: _orderDate = value; 32: } 33: } Finally you also need to create the EntityState property as follows: 1: public EntityState EntityState 2: { 3: get { return _changeTracker.EntityState; } 4: } The IEntityWithRelationships involves creating a property that returns RelationshipManager object: 1: public RelationshipManager RelationshipManager 2: { 3: get 4: { 5: if (_relManager == null) 6: _relManager = RelationshipManager.Create(this); 7: return _relManager; 8: } 9: } ============================================================ Tip : ProviderManifestToken – change EDMX File to use SQL 2008 instead of SQL 2005 To use with SQL Server 2008, edit the EDMX file (the raw XML) changing the ProviderManifestToken in the SSDL attributes from "2005" to "2008" ============================================================= With EFv1 we cannot use Structs to replace a anonymous Type while doing projections in a LINQ to Entities query. While the same is supported with LINQToSQL, it is not with LinqToEntities. For e.g. the following is not supported with LinqToEntities since only parameterless constructors and initializers are supported in LINQ to Entities. (the same works with LINQToSQL) 1: public struct CompanyInfo 2: { 3: public int ID { get; set; } 4: public string Name { get; set; } 5: } 6: var companies = (from c in dc.Companies 7: where c.CompanyIcon == null 8: select new CompanyInfo { Name = c.CompanyName, ID = c.CompanyId }).ToList(); ;

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  • Twitter Integration in Windows 8

    - by Joe Mayo
    Glenn Versweyveld, @Depechie, blogged about Twitter Integration in Windows 8. The post describes how to use WinRtAuthorizer to perform OAuth authentication with LINQ to Twitter. If you’re using LINQ to Twitter with Windows 8, the WinRtAuthorizer is definitely the way to go. It lets you perform the entire OAuth dance with a single method call, which is a huge time savings and simplification of your code. In addition to Glenn’s excellent post, I’ve posted a sample app named MetroWinRtAuthorizerDemo.zip on the LINQ to Twitter Samples Page. @JoeMayo

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  • Developing for 2005 using VS2008!

    - by Vincent Grondin
    I joined a fairly large project recently and it has a particularity… Once finished, everything has to be sent to the client under VS2005 using VB.Net and can target either framework 2.0 or 3.0… A long time ago, the decision to use VS2008 and to target framework 3.0 was taken but people knew they would need to establish a few rules to ensure that each dev would use VS2008 as if it was VS2005… Why is that so? Well simply because the compiler in VS2005 is different from the compiler inside VS2008…  I thought it might be a good idea to note the things that you cannot use in VS2008 if you plan on going back to VS2005. Who knows, this might save someone the headache of going over all their code to fix errors… -        Do not use LinQ keywords (from, in, select, orderby…).   -        Do not use LinQ standard operators under the form of extension methods.   -        Do not use type inference (in VB.Net you can switch it OFF in each project properties). o   This means you cannot use XML Literals.   -        Do not use nullable types under the following declarative form:    Dim myInt as Integer? But using:   Dim myInt as Nullable(Of Integer)     is perfectly fine.   -        Do not test nullable types with     Is Nothing    use    myInt.HasValue     instead.   -        Do not use Lambda expressions (there is no Lambda statements in VB9) so you cannot use the keyword “Function”.   -        Pay attention not to use relaxed delegates because this one is easy to miss in VS2008   -        Do not use Object Initializers   -        Do not use the “ternary If operator” … not the IIf method but this one     If(confition, truepart, falsepart).   As a side note, I talked about not using LinQ keyword nor the extension methods but, this doesn’t mean not to use LinQ in this scenario. LinQ is perfectly accessible from inside VS2005. All you need to do is reference System.Core, use namespace System.Linq and use class “Enumerable” as a helper class… This is one of the many classes containing various methods that VS2008 sees as extensions. The trick is you can use them too! Simply remember that the first parameter of the method is the object you want to query on and then pass in the other parameters needed… That’s pretty much all I see but I could have missed a few… If you know other things that are specific to the VS2008 compiler and which do not work under VS2005, feel free to leave a comment and I’ll modify my list accordingly (and notify our team here…) ! Happy coding all!

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  • Namespace Problem

    - by Tarik
    Hello, Normally we all do use using System.Linq; and using System.Data.Linq; for example on the code-behind and expect we can reach the members of these namespaces from Source Code like <%= Something.First()%> but when I wrote it, asp.net said it couldn't find First() in the context and I had to add <%@ Import Namespace="System.Linq" which looked very weird to me but it worked out. Since they are targeting at the same class why they both need separate namespace importing. Code-behind : using System; using System.Data.Linq; using System.Linq; using System.Text namespace Something { class Items : System.Web.UI { //... } } but also I need to add the same Linq namespace on the Html Source part <%@Import Namespace="System.Linq"%> Do I know something wrong or this is some kind of bug in asp.net. I thought when the page is compiling, asp.net combines these two classes and converts html source code into cs class and indicates the control in Control c= new Control(); hierarchy. Thanks in advance.

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  • Asp.Net Random Error

    - by John Boker
    At random times, twice in the past two weeks, the we application will start to error and not work until I recycle the app pool in IIS. The specific error and stacktrace are: System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.InvalidCastException: Unable to cast object of type 'System.Guid' to type 'System.String'. at System.Data.Linq.SqlClient.SqlProvider.Execute(Expression query, QueryInfo queryInfo, IObjectReaderFactory factory, Object[] parentArgs, Object[] userArgs, ICompiledSubQuery[] subQueries, Object lastResult) at System.Data.Linq.SqlClient.SqlProvider.ExecuteAll(Expression query, QueryInfo[] queryInfos, IObjectReaderFactory factory, Object[] userArguments, ICompiledSubQuery[] subQueries) at System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) at System.Data.Linq.DataQuery`1.System.Linq.IQueryProvider.Execute[S](Expression expression) at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source) at DigitalScout.WEDS.Business.Slug.GetTeamPath(String teamID) at DigitalScout.WEDS.WebApp.Code.Navigator.TeamNavigator.Home(String teamID) at ASP.management_default_aspx.__DataBind__control7(Object sender, EventArgs e) at System.Web.UI.Control.OnDataBinding(EventArgs e) at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.Control.DataBindChildren() at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource) at System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e) at System.Web.UI.Control.DataBindChildren() at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding) at System.Web.UI.WebControls.Repeater.CreateControlHierarchy(Boolean useDataSource) at System.Web.UI.WebControls.Repeater.OnDataBinding(EventArgs e) at DigitalScout.WEDS.WebApp.Management._default.Page_Load(Object sender, EventArgs e) at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) at System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) at System.Web.UI.Control.OnLoad(EventArgs e) at DigitalScout.WEDS.WebApp.Code.BaseClass.Pages.ManagementPage.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace --- at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest() at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.management_default_aspx.ProcessRequest(HttpContext context) at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) This error happens for every user of the system until the app pool is recycled. Any help on this would be helpful as we are not able to reproduce the error.

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  • How do I create queries to SQL Server tables via Visual Studio when no knowledge about SQL nor Linq?

    - by Kent S. Clarkson
    Let´s be frank, my knowledge regarding SQL language is very low. Nevertheless, my boss gave me the task to build a database application using the following tools: SQL Server and Visual Studio 2008; C#. I use the VS DataSet as a local mirror of the SQL Server. And let´s be frank again, my understanding of the VS Query builder is also very small, I´m finding it quite confusing, actually. So no help to find from Query builder. And my knowledge of Linq is even lower... Perhaps I should mention that the deadline for the project is "aggressively" set, so I have no chance to learn enough about these things during the project. And I´m a bit stupid too, which is no help when it comes to challenges like this (on other occations it might be quite useful though) With these permissions, what should I do (except for killing myself or retire) to be able to query my tables in a sufficient way?

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  • Problem showing selected value of combobox when it is bind to a List<T> using Linq to Entities

    - by Syed Mustehsan Ikram
    I have a combobox which is has itemtemplate applied on it and is bind to a List of entity return using linq. i m using mvvm. It is bind to it successfully but when i set the selected value of it from code at runtime to show the selected value coming from db it doesn't select it. For reference here is my combobox xaml. SelectedValue="{Binding Path=SelectedManufacturer}" Grid.Column="3" Grid.Row="2" Margin="20,9.25,68,7.75" ItemTemplate="{StaticResource ManufacturerDataTemplate}" TabIndex="6"/ Here is my part from code behind from viewModel. List currentManufacturers = new List(); tblManufacturer selectedManufacturer = null; public List CurrentManufacturers { get { return currentManufacturers; } set { currentManufacturers = value; NotifyPropertyChanged("CurrentManufacturers"); } } public tblManufacturer SelectedManufacturer { get { return selectedManufacturer; } set { selectedManufacturer = currentManufacturers.Where(mm => mm.ManufacturerID == Convert.ToInt32(selectedDevice.tblManufacturer.EntityKey.EntityKeyValues[0].Value)).First(); NotifyPropertyChanged("SelectedManufacturer"); } }

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  • How can i Write list type returning value in Linq with Entity FrameWork?

    - by programmerist
    How can i return List<personel> data type from below procedure. if i press F5 it throw me this error: Error 1 Cannot implicitly convert type 'System.Linq.IQueryable' to 'System.Collections.Generic.List'. An explicit conversion exists (are you missing a cast?) C:\Documents and Settings\yusufk\Desktop\EFTestSolutions\WebApplicationTest1\WebApplicationTest1\Default.aspx.cs 101 61 WebApplicationTest1 i think that: i should rearrange or recode "select new {. . . . " ? protected List<personel> GetPersonalsData2() { List<personel> personeller; using (FirmaEntities firmactx = new FirmaEntities()) { personeller = (from p in firmactx.Personals select new { p.ID, p.Name, p.SurName }); return personeller.ToList(); } } } public class personel { public int ID { get; set; } public string Name { get; set; } public string SurName { get; set; } }

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  • Why is PLINQ slower than LINQ for this code?

    - by Rob Packwood
    First off, I am running this on a dual core 2.66Ghz processor machine. I am not sure if I have the .AsParallel() call in the correct spot. I tried it directly on the range variable too and that was still slower. I don't understand why... Here are my results: Process non-parallel 1000 took 146 milliseconds Process parallel 1000 took 156 milliseconds Process non-parallel 5000 took 5187 milliseconds Process parallel 5000 took 5300 milliseconds using System; using System.Collections.Generic; using System.Diagnostics; using System.Linq; namespace DemoConsoleApp { internal class Program { private static void Main() { ReportOnTimedProcess( () => GetIntegerCombinations(), "non-parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(runAsParallel: true), "parallel 1000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000), "non-parallel 5000"); ReportOnTimedProcess( () => GetIntegerCombinations(5000, true), "parallel 5000"); Console.Read(); } private static List<Tuple<int, int>> GetIntegerCombinations( int iterationCount = 1000, bool runAsParallel = false) { IEnumerable<int> range = Enumerable.Range(1, iterationCount); IEnumerable<Tuple<int, int>> integerCombinations = from x in range from y in range select new Tuple<int, int>(x, y); return runAsParallel ? integerCombinations.AsParallel().ToList() : integerCombinations.ToList(); } private static void ReportOnTimedProcess( Action process, string processName) { var stopwatch = new Stopwatch(); stopwatch.Start(); process(); stopwatch.Stop(); Console.WriteLine("Process {0} took {1} milliseconds", processName, stopwatch.ElapsedMilliseconds); } } }

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  • Get Application Title from Windows Phone

    - by psheriff
    In a Windows Phone application that I am currently developing I needed to be able to retrieve the Application Title of the phone application. You can set the Deployment Title in the Properties of your Windows Phone Application, however getting to this value programmatically can be a little tricky. This article assumes that you have Visual Studio 2010 and the Windows Phone tools installed along with it. The Windows Phone tools must be downloaded separately and installed with Visual Studio2010. You may also download the free Visual Studio2010 Express for Windows Phone developer environment. The WMAppManifest.xml File First off you need to understand that when you set the Deployment Title in the Properties windows of your Windows Phone application, this title actually gets stored into an XML file located under the \Properties folder of your application. This XML file is named WMAppManifest.xml. A portion of this file is shown in the following listing. <?xml version="1.0" encoding="utf-8"?><Deployment  http://schemas.microsoft.com/windowsphone/2009/deployment"http://schemas.microsoft.com/windowsphone/2009/deployment"  AppPlatformVersion="7.0">  <App xmlns=""       ProductID="{71d20842-9acc-4f2f-b0e0-8ef79842ea53}"       Title="Mobile Time Track"       RuntimeType="Silverlight"       Version="1.0.0.0"       Genre="apps.normal"       Author="PDSA, Inc."       Description="Mobile Time Track"       Publisher="PDSA, Inc."> ... ...  </App></Deployment> Notice the “Title” attribute in the <App> element in the above XML document. This is the value that gets set when you modify the Deployment Title in your Properties Window of your Phone project. The only value you can set from the Properties Window is the Title. All of the other attributes you see here must be set by going into the XML file and modifying them directly. Note that this information duplicates some of the information that you can also set from the Assembly Information… button in the Properties Window. Why Microsoft did not just use that information, I don’t know. Reading Attributes from WMAppManifest I searched all over the namespaces and classes within the Windows Phone DLLs and could not find a way to read the attributes within the <App> element. Thus, I had to resort to good old fashioned XML processing. First off I created a WinPhoneCommon class and added two static methods as shown in the snippet below: public class WinPhoneCommon{  /// <summary>  /// Returns the Application Title   /// from the WMAppManifest.xml file  /// </summary>  /// <returns>The application title</returns>  public static string GetApplicationTitle()  {    return GetWinPhoneAttribute("Title");  }   /// <summary>  /// Returns the Application Description   /// from the WMAppManifest.xml file  /// </summary>  /// <returns>The application description</returns>  public static string GetApplicationDescription()  {    return GetWinPhoneAttribute("Description");  }   ... GetWinPhoneAttribute method here ...} In your Windows Phone application you can now simply call WinPhoneCommon.GetApplicationTitle() or WinPhone.GetApplicationDescription() to retrieve the Title or Description properties from the WMAppManifest.xml file respectively. You notice that each of these methods makes a call to the GetWinPhoneAttribute method. This method is shown in the following code snippet: /// <summary>/// Gets an attribute from the Windows Phone WMAppManifest.xml file/// To use this method, add a reference to the System.Xml.Linq DLL/// </summary>/// <param name="attributeName">The attribute to read</param>/// <returns>The Attribute's Value</returns>private static string GetWinPhoneAttribute(string attributeName){  string ret = string.Empty;   try  {    XElement xe = XElement.Load("WMAppManifest.xml");    var attr = (from manifest in xe.Descendants("App")                select manifest).SingleOrDefault();    if (attr != null)      ret = attr.Attribute(attributeName).Value;  }  catch  {    // Ignore errors in case this method is called    // from design time in VS.NET  }   return ret;} I love using the new LINQ to XML classes contained in the System.Xml.Linq.dll. When I did a Bing search the only samples I found for reading attribute information from WMAppManifest.xml used either an XmlReader or XmlReaderSettings objects. These are fine and work, but involve a little extra code. Instead of using these, I added a reference to the System.Xml.Linq.dll, then added two using statements to the top of the WinPhoneCommon class: using System.Linq;using System.Xml.Linq; Now, with just a few lines of LINQ to XML code you can read to the App element and extract the appropriate attribute that you pass into the GetWinPhoneAttribute method. Notice that I added a little bit of exception handling code in this method. I ignore the exception in case you call this method in the Loaded event of a user control. In design-time you cannot access the WMAppManifest file and thus an exception would be thrown. Summary In this article you learned how to retrieve the attributes from the WMAppManifest.xml file. I use this technique to grab information that I would otherwise have to hard-code in my application. Getting the Title or Description for your Windows Phone application is easy with just a little bit of LINQ to XML code. NOTE: You can download the complete sample code at my website. http://www.pdsa.com/downloads. Choose Tips & Tricks, then "Get Application Title from Windows Phone" from the drop-down. Good Luck with your Coding,Paul Sheriff ** SPECIAL OFFER FOR MY BLOG READERS **Visit http://www.pdsa.com/Event/Blog for a free video on Silverlight entitled Silverlight XAML for the Complete Novice - Part 1.  

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