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• Why should I use MVVM when it breaks built in functionality

  - by Jakob

  I'm struggling to grasp why MVVM is really a good pattern to implement in riaserivces, To me there's nothing but trouble to it, it just add's another tier that I have to code. I Get that I could change the UI, but really I don't need to. Instead i won't be able to user out of the box functionality with riaservices, datagrid, dataform all controls require some implementation. Why can't it just be simple? Is there really no way to get MVVM to automatically set "IsBusy" and all the dataform edit functionality. It's like reinventing the wheel to me, and it seems that I'd be able to write code much faster just using riaservices

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• VS 2010 Entity Repository Error Class member EntityBase.id is unmapped.

  - by Steve

  In my project I have it set up so that all the tables in the DB has the property "id" and then I have the entity objects inherit from the EntityBase class using a repository pattern. I then set the inheritance modifier for "id" property in the dbml file o/r designer to "overrides" Public MustInherit Class EntityBase MustOverride Property id() As Integer End Class Public MustInherit Class RepositoryBase(Of T As EntityBase) Protected _Db As New DataClasses1DataContext Public Function GetById(ByVal Id As Integer) As T Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault End Function End Class Partial Public Class Entity1 Inherits EntityBase End Class Public Class TestRepository Inherits RepositoryBase(Of Entity1) End Class the line Return (From a In _Db.GetTable(Of T)() Where a.id = Id).SingleOrDefault however produces the error "Class member EntityBase.id is unmapped" when i use VS 2010 using the 4.0 framework but I never received that error with the old one. Any help would be greatly appreciated. Thanks in advance.

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• Is it a bad idea to use the new Dynamic Keyword as a replacement switch statement?

  - by WeNeedAnswers

  I like the new Dynamic keyword and read that it can be used as a replacement visitor pattern. It makes the code more declarative which I prefer. Is it a good idea though to replace all instances of switch on 'Type' with a class that implements dynamic dispatch. class VistorTest { public string DynamicVisit(object obj) { return Visit((dynamic)obj); } private string Visit(string str) { return "a string was called with value " + str; } private string Visit(int value) { return "an int was called with value " + value; } }

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• Dynamically loading JavaScript synchronously

  - by spoon16

  I'm using the module pattern, one of the things I want to do is dynamically include an external JavaScript file, execute the file, and then use the functions/variables in the file in the return { } of my module. I can't figure out how to do this easily. Are there any standard ways of performing a pseudo synchronous external script load? function myModule() { var tag = document.createElement("script"); tag.type = "text/javascript"; tag.src = "http://some/script.js"; document.getElementsByTagName('head')[0].appendChild(tag); //something should go here to ensure file is loaded before return is executed return { external: externalVariable } }

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• SELECT with a Replace()

  - by andyjohnson

  I have a table of names and addresses, which includes a postcode column. I want to strip the spaces from the postcodes and select any that match a particular pattern. I'm trying this (simplified a bit) in T-SQL on SQL Server 2005: SELECT Replace(Postcode, ' ', '') AS P FROM Contacts WHERE P LIKE 'NW101%' But I get the following error; Msg 207, Level 16, State 1, Line 3 Invalid column name 'P'. If I remove the WHERE clause I get a list of postcodes without spaces, which is what I want to search. How should I approach this? What am I doing wrong?

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• regular expression and escaping

  - by pstanton

  Sorry if this has been asked, my search brought up many off topic posts. I'm trying to convert wildcards from a user defined search string (wildcard is "*") to postgresql like wildcard "%". I'd like to handle escaping so that "%" => "\%" and "\*" => "*" I know i could replace \* with something else prior to replacing * and then swap it back, but i'd prefer not to and instead only convert * using a pattern that selects it when not proceeded by \. String convertWildcard(String like) { like = like.replaceAll("%", "\\%"); like = like.replaceAll("\\*", "%"); return like; } Assert.assertEquals("%", convertWildcard("*")); Assert.assertEquals("\%", convertWildcard("%")); Assert.assertEquals("*", convertWildcard("\*")); // FAIL Assert.assertEquals("a%b", convertWildcard("a*b")); Assert.assertEquals("a\%b", convertWildcard("a%b")); Assert.assertEquals("a*b", convertWildcard("a\*b")); // FAIL ideas welcome.

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• Help me understand Dispose() implementation code from MSDN

  - by Benny

  the following code is from MSDN: Idisposable pattern protected virtual void Dispose(bool disposing) { // If you need thread safety, use a lock around these // operations, as well as in your methods that use the resource. if (!_disposed) { if (disposing) { if (_resource != null) _resource.Dispose(); Console.WriteLine("Object disposed."); } // Indicate that the instance has been disposed. _resource = null; _disposed = true; } } why the following statement: _resource = null; _disposed = true; are not enclosed by if (disposing) statement block? for me i would probably write like this: if (disposing) { if (_resource != null) { _resource.Dispose(); _resource = null; _disposed = true; } Console.WriteLine("Object disposed."); } anything wrong with my version?

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• Can we create a class from a xml file ?

  - by panzerschreck

  Hello, Is it possible to create a class dynamically by reading an xml file ( in java preferably) ? if yes, please provide pointers on how to do it. In the process of development, we have come up with a class that has 5 attributes, all these attributes correspond to an entry in the xml file, now if the user adds/modifies the xml entry the object corresponding to it must change automatically, one approach would be generate the source code, before compile time.Is there any other way ? Is there any common pattern to model such changes in the system ? Thanks,

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• how to fetch a range of files from an FTP server using C#

  - by user260076

  hello all, i'm stuck at a point where i am using a wildcard parameter with the FtpWebRequest object as suck FtpWebRequest reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServerIP + "/" + WildCard)); now this works fine, however i now want to fetch a specific range of files. say the file naming structure is *YYYYMMDD.* and i need to fetch all the files prior to today's date. i've been searching for a wildcard pattern for that with no good results, one that will work in a simple file listing. and it doesn't look like i can use regex here. any thoughts ?

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• Data access strategy for a site like SO - sorted SQL queries and simultaneous updates that affect th

  - by Kaleb Brasee

  I'm working on a Grails web app that would be similar in access patterns to StackOverflow or MyLifeIsAverage - users can vote on entries, and their votes are used to sort a list of entries based on the number of votes. Votes can be placed while the sorted select queries are being performed. Since the selects would lock a large portion of the table, it seems that normal transaction locking would cause updates to take forever (given enough traffic). Has anyone worked on an app with a data access pattern such as this, and if so, did you find a way to allow these updates and selects to happen more or less concurrently? Does anyone know how sites like SO approach this? My thought was to make the sorted selects dirty reads, since it is acceptable if they're not completely up to date all of the time. This is my only idea for possibly improving performance of these selects and updates, but I thought someone might know a better way.

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• Asynchrous calls cause StaleObjectStateException

  - by Mulone

  Hi all, I'm struggling with a Grails service. The service gets AJAX calls from the clients and behaves like a simple local cache for remote objects: void **someCallFromClient**() { // extract params def results = remoteService.queryService(params) results.each{ // try to fetch result object from local DB def obj = SomeClass.findBySomeField(result.someField) if (!obj){ obj = new Result(params) obj.save() } // do stuff on obj } } The service works fine when only one client is connected, but as soon as 2 or more clients start bombing the server with requests, I start getting: 2010-05-24 13:09:49,764 [30893094@qtp-26315919-2] ERROR errors.GrailsExceptionResolver - Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [ some object #892901] org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): [ some object #892901] // very long stactrace It probably happens when 2 calls are trying to create the same object concurrently. I suppose this is a rather typical situation to end up in. Could you recommend any pattern/good practice to fix this issue? For example, is there a way to say to one of the service instances to hang on and wait for the other to finish its stuff and try again? Cheers!

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• Cancelling Two Way Data Binding In Silverlight

  - by DaveB

  I have an ObervableCollection of data items. This collection is bound to a ListBox. When the user selects a item from the listbox and clicks the Edit button a UserControl with the details of that item is displayed with the various properties bound to text boxes. Each binding mode is set for TwoWay. On this details UserControl, I would like to implement 2 buttons, OK and Cancel. This would be consistent with UIs in Windows. This application is using the Model-View_ViewModel pattern. Here is my question: 1) How can I implement the Cancel button when all the changes have already been committed?

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• What is the fastest way to scrape HTML webpage in Android?

  - by kunjaan

  I need to extract information from an unstructured web page in Android. The information I want is embedded in a table that doesn't have an id. <table> <tr><td>Description</td><td></td><td>I want this field next to the description cell</td></tr> </table> Should I use Pattern Matching? Use BufferedReader to extract the information? Or are there faster way to get that information?

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• String Functions in IIS Url Rewritting Module

  - by Nariman

  The IIS URL Rewrite Module ships with 3 built-in functions: * ToLower - returns the input string converted to lower case. * UrlEncode - returns the input string converted to URL-encoded format. This function can be used if the substitution URL in rewrite rule contains special characters (for example non-ASCII or URI-unsafe characters). * UrlDecode - decodes the URL-encoded input string. This function can be used to decode a condition input before matching it against a pattern. The functions can be invoked by using the following syntax: {function_name:any_string} The question is: can this list be extended by introducing a Replace function that's available for changing values within a rewrite rule action or condition?

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• What are some of the useful concepts to know about when building Silverlight apps?

  - by cody

  The Silverlight(& WPF) space seems to have a whole new nomenclature around it so at times I'm having a hard time figuring our what is important and useful to research a bit more. For example I 'know' about the MVVM pattern but I'm looking for things that are a bit smaller in scope, that is topics, ideas, programming constructs that might be used in implementing MVVM and would need to know before hand. So basically I'm looking for some of the key topics and concepts that people have found useful or are important when creating a Silverlight apps. And maybe why it is useful or important and when\where it might be applied or used. Thanks.

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• Store interface in array list java

  - by agazerboy

  Hi all, I am learning java. I am trying to use composite design pattern. I am trying to use following logic. ( Don't laugh I know it is very basic :) ) Item -> interface Folder -> class File -> class In folder class, can I create an arraylist of Item to store files information? ArrayList<Item> info = ArrayList<Item>(); Or should I use Folder Arraylist? ArrayList<Folder> info = ArrayList<Folder>(); I don't know if interface can store real data as there is no variable just function definitions. Thanks for helping a newbie :)

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• How, in general, can web framework support REST style?

  - by juro

  I would like to know, what are the ways a web framework may be suitable for designing a RESTful app, in general. One goal is for example to provide http request routing, so they are automatically sent to appropriate controllers. From architectural point of view, web framework based on MVC pattern are more suitable for REST. What other features of web frameworks are helpful by building apps satisfying the REST constraints? Is there any reason why you consider certain languages(python/java) or web frameworks(django/turbogears/jersey/restlets/...) as the most applicable ones?

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• How do I determine inactivity in a MVVM application?

  - by Jordan

  I have an MVVM kiosk application that I need to restart when it has been inactive for a set amount of time. I'm using Prism and Unity to facilitate the MVVM pattern. I've got the restarting down and I even know how to handle the timer. What I want to know is how to know when activity, that is any mouse event, has taken occurred. The only way I know how to do that is by subscribing to the preview mouse events of the main window. That breaks MVVM thought, doesn't it? I've thought about exposing my window as an interface that exposes those events to my application, but that would require that the window implement that interface which also seems to break MVVM.

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• silverlight vs ASP.NET MVC

  - by magellings

  I'm debating whether to use Silverlight 2.0 vs ASP.NET MVC for a web application. The web application will be a subscription free service marketing all age groups. It's important the source is highly testable, but also with the Web 2.0 movement a graphical web application is important as well for competitive reasons. I'm assuming silverlight is better than the ajax helpers/MVC graphically, but foundation-wise testing is better/easier with MVC. Possibly an MVP pattern with Silverlight could increase the testability of the source. Could anyone elaborate on the pros/cons of each technology and recommend one or the other based on the above? (addition 9/22/08) In regards to allowing search engines to index the site, using either technology it will utilize a backend database whereas a lot of the content will be dynamically generated. Based on some of the comments, when we talk of the searchable content would the home page of the application if written in silverlight be searchable? Would I be able to get the site to appear in a google search?

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• Avoiding configSections in .NET app.config files

  - by Chris Clark

  I'm looking for a way to avoid declaring my configuration section in the configSections inside the App.config file. Basically, I want to specify my configuration information just like I do for built-in .NET systems. For instance, when configuring WCF, I just put stuff in the <system.serviceModel>, I don't have to declare a section in the configSections up top. The same thing applies for <system.diagnostics> and many other namespaces. I know I could just load it up as an XML file and parse through it, but I'd prefer to stick with the pattern if possible. Moreover, looking at the WCF configuration with Reflector, I notice that it uses the same configuration subsystem (defined in System.Configuration). If you're wondering why this is important, it's because it's confusing our IT people. If it were self contained in one place, it would be much easier on them. I also realize I'll lose the ability to have multiple of the same section type, but that's not important in our case.

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• How can I make CAPTCHA work across multiple pages?

  - by jm04469

  Ever visit a website such as myspace where they leverage CAPTCHA to prevent spam? The typical pattern is to present a challenge to each URL that is opened, yet the challenge doesn't actually belong to the page itself which causes additional bandwidth usage. So, if I open up six pages at the same time and want to present a challenge on each page. I want the challenge to be tied to the page and not to the session. How can I make this work with Spring and/or Struts.

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• How to solve the "Growing If Statement" problem?

  - by Achilles

  I've been doing some reading about design patterns and wanted some perspective. Consider the following: Dim objGruntWorker as IGruntWorker if SomeCriteria then objGruntWorker = new GoFor() else if SomeOtherCriteria then objGruntWorker = new Newb() else if SomeCriteriaAndTheKitchenSink then objGruntWorker = new CubeRat() end if objGruntWorker.GetBreakfast() system.threading.thread.sleep(GetMilliSecondsFromHours(4)) objGruntWorker.GetLunch() The above code grows each time a new Criteria arises. I've seen code like this all over the place and in ignorance wrote some of it myself. How should this be solved? Does this kind of anti-pattern have a more "formal" name? Thanks for your help!

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• How to deal with the new line character in the Silverlight TextBox

  - by Ian Oakes

  When using a multi-line TextBox (AcceptsReturn="True") in Silverlight, line feeds are recorded as \r rather than \r\n. This is causing problems when the data is persisted and later exported to another format to be read by a Windows application. I was thinking of using a regular expression to replace any single \r characters with a \r\n, but I suck at regex's and couldn't get it to work. Because there may be a mixture of line endings just blindy replacing all \r with \r\n doesn't cut it. So two questions really... If regex is the way to go what's the correct pattern? Is there a way to get Silverlight to respect it's own Environment.NewLine character in TextBox's and have it insert \r\n rather just a single \r?

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• Reusability, testability, code complexity reduction and showing-off-ability programming importance

  - by Andrew Florko

  There are lots of programming and architecture patterns. Patterns allow to make code cleaner, reusable, more testable & at last (but not at least) to feel the follower a real cool developer. How do you rank these considerations for you? What does affect you most when you decide to apply pattern? I wonder how many times code reusability (especially for MVP, MVC patterns) was important? For example DAL library often shared between projects (it's reusable) but how often controllers/views (abstracted via interfaces) are reused?

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• CommandManager "cannot resolve symbol"

  - by Budda

  After adding "RelayCommand" class (that uses CommandManager class) into my Silverlight App I've got an error: The name 'CommandManager' does not exist in the current context This class is a member of System.Windows.Input namespace that is in PresentationCore.dll assembly. The problem is that I can't add this dll into my app... I am having a strange assumption: this class (CommmandManager) can't be used in the Silverlight. Am I right? How can I implement MVVM-pattern (http://msdn.microsoft.com/en-us/magazine/dd419663.aspx)? Thanks.

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