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  • Count number of given object in a list with LINQ

    - by Aaginor
    I have a list which can contain multiple occurrences of the same object. Now I need to count, how often the given object is contained in this list. int count = 0; foreach (IMyObject item in myList) if (item == object2Count) count++; I am sure that this can be done nicer with LINQ, but LINQ is still a mystery to me. My first question is: How would I count the objects via LINQ and the second question: Will this LINQ version be slower or faster? I am using a ObservableCollection and the number of items in the list is usally rather small ... usally not more then 20. Thanks in advance, Frank

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  • Using Linq to SQL change events with attribute-based mapping

    - by R Mene
    I'm writing a new ASP.NET MVC2 application using Linq to SQL. This application depends on an existing SQL database. I am using attribute-based mapping to map my database fields to my Linq to SQL entities. I also need to make use of Linq to SQL's On[Property]Changed methods so I can perform change-auditing of database tables within my application. Whereas the documentation explains how to do this when using Linq to SQL's ORM and dbml files (i.e. by writing partial classes), it is not clear how to do with when using attribute-based mapping or when using XML-based mapping. It would be very helpful if someone could describe how to do this.

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  • How to user IN operator in Linq?

    - by Umapathy
    Query: Select * from pu_Products where Part_Number in ('031832','027861', '028020', '033378') and User_Id = 50 and Is_Deleted = 0 The above mentioned query is in SQL and i need the query might be converted into Linq. Is there any option using the "IN" operator in Linq?. can you convert above mentioned query into Linq?

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  • Translate an IQueryable instance to LINQ syntax in a string

    - by James Dunne
    I would like to find out if anyone has existing work surrounding formatting an IQueryable instance back into a LINQ C# syntax inside a string. It'd be a nice-to-have feature for an internal LINQ-to-SQL auditing framework I'm building. Once my framework gets the IQueryable instance from a data repository method, I'd like to output something like: This LINQ query: from ce in db.EiClassEnrollment join c in db.EiCourse on ce.CourseID equals c.CourseID join cl in db.EiClass on ce.ClassID equals cl.ClassID join t in db.EiTerm on ce.TermID equals t.TermID join st in db.EiStaff on cl.Instructor equals st.StaffID where (ce.StudentID == studentID) && (ce.TermID == termID) && (cl.Campus == campusID) select new { ce, cl, t, c, st }; Generates the following LINQ-to-SQL query: DECLARE @p0 int; DECLARE @p1 int; DECLARE @p2 int; SET @p0 = 777; SET @p1 = 778; SET @p2 = 779; SELECT [t0].[ClassEnrollmentID], ..., [t4].[Name] FROM [dbo].[ei_ClassEnrollment] AS [t0] INNER JOIN [dbo].[ei_Course] AS [t1] ON [t0].[CourseID] = [t1].[CourseID] INNER JOIN [dbo].[ei_Class] AS [t2] ON [t0].[ClassID] = [t2].[ClassID] INNER JOIN [dbo].[ei_Term] AS [t3] ON [t0].[TermID] = [t3].[TermID] INNER JOIN [dbo].[ei_Staff] AS [t4] ON [t2].[Instructor] = [t4].[StaffID] WHERE ([t0].[StudentID] = @p0) AND ([t0].[TermID] = @p1) AND ([t2].[Campus] = @p2) I already have the SQL output working as you can see. I just need to find a way to get the IQueryable to translate into a string representing its original LINQ syntax (with an acceptable translation loss). I'm not afraid of writing it myself, but I'd like to see if anyone else has done this first.

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  • Download LINQPad to learn LINQ

    - by Editor
    LINQPad lets you interactively query SQL databases in a modern query language: LINQ. Say goodbye to SQL Management Studio.LINQPad supports everything in C# 3.0 and Framework 3.5: LINQ to SQL LINQ to Objects LINQ to XML LINQPad is also a great way to learn LINQ: it comes preloaded with 200 examples from the book, C# [...]

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  • When it's more productive to build your own framework than using an existing one?

    - by Pierre 303
    I would like to know why you decided to build your own framework in your company. By framework, I don't mean few libraries you use often. I mean a specific way of building applications on top of it, with base classes, convention, etc. So why did you built your own framework? How could you justify that to the person that employs you. Have you measure the positive and negative impact of it? Regarding your experiences, did you notice that in some case a company framework produced real benefits, or on the other hand, increased costs of development (learning curve, debugging, maintenance, ...)?

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  • What would be the market life of a JVM based software framework?

    - by Nav
    I saw how Struts 1 lasted from 2000 to 2013. I hear that people are moving from Struts 2 to Spring. But for a project that may need to be maintained for a decade or two, would it be advisable to opt for a framework or directly code with servlets and jquery? Can a system architecture really be designed keeping in mind a particular framework? What really is the market life of a framework? Do the creators of the framework create it with the assumption that it would become obsolete in a decade?

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  • why does entity framework+mysql provider enumeration returns partial results with no exceptions

    - by Freddy Rios
    I'm trying to make sense of a situation I have using entity framework on .net 3.5 sp1 + MySQL 6.1.2.0 as the provider. It involves the following code: Response.Write("Products: " + plist.Count() + "<br />"); var total = 0; foreach (var p in plist) { //... some actions total++; //... other actions } Response.Write("Total Products Checked: " + total + "<br />"); Basically the total products is varying on each run, and it isn't matching the full total in plist. Its varies widely, from ~ 1/5th to half. There isn't any control flow code inside the foreach i.e. no break, continue, try/catch, conditions around total++, anything that could affect the count. As confirmation, there are other totals captured inside the loop related to the actions, and those match the lower and higher total runs. I don't find any reason to the above, other than something in entity framework or the mysql provider that causes it to end the foreach when retrieving an item. The body of the foreach can have some good variation in time, as the actions involve file & network access, my best shot at the time is that when the .net code takes beyond certain threshold there is some type of timeout in the underlying framework/provider and instead of causing an exception it is silently reporting no more items for enumeration. Can anyone give some light in the above scenario and/or confirm if the entity framework/mysql provider has the above behavior? Update: I can't reproduce the behavior by using Thread.Sleep in a simple foreach in a test project, not sure where else to look for this weird behavior :(.

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  • Unable to install .NET Framework 3.5 to my XP machine

    - by CptanPanic
    I have an application that requires .NET 3.5, but I can't install it. The installer quits saying "it has encoutered a problem during setup. If I look at some of the error logs in the tmp directory I see. Error occurred while initializing fusion. It seems that I have 2.0 SP1 installed. Any ideas how I can get it to work? I went through the temp directory and found these references to the error. Any ideas? [04/17/12,18:55:09] Microsoft .NET Framework 2.0a: [2] Error: Installation failed for component Microsoft .NET Framework 2.0a. MSI returned error code 1603 [04/17/12,18:55:27] WapUI: [2] DepCheck indicates Microsoft .NET Framework 2.0a is not installed. 04/19/12 19:08:48 DDSet_Status: Loading fusion.dll using LoadLibraryShim() 04/19/12 19:08:48 DDSet_Error: Error occurred while initializing fusion. Setup could not load fusion with LoadLibraryShim(). Error: 0x80131700 04/19/12 19:08:48 DDSet_Status: Loading fusion.dll using LoadLibraryShim() 04/19/12 19:08:48 DDSet_Error: Error occurred while initializing fusion. Setup could not load fusion with LoadLibraryShim(). Error: 0x80131700 MSI (s) (74!08) [19:08:48:062]: Product: Microsoft .NET Framework 2.0 Service Pack 1 -- Error 25007.Error occurred while initializing fusion. Setup could not load fusion with LoadLibraryShim(). Error: 0x80131700 Error 25007.Error occurred while initializing fusion. Setup could not load fusion with LoadLibraryShim(). Error: 0x80131700

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  • Entity Framework SaveChanges error details

    - by Marek Karbarz
    When saving changes with SaveChanges on a data context is there a way to determine which Entity causes an error? For example, sometimes I'll forget to assign a date to a non-nullable date field and get "Invalid Date Range" error, but I get no information about which entity or which field it's caused by (I can usually track it down by painstakingly going through all my objects, but it's very time consuming). Stack trace is pretty useless as it only shows me an error at the SaveChanges call without any additional information as to where exactly it happened. Note that I'm not looking to solve any particular problem I have now, I would just like to know in general if there's a way to tell which entity/field is causing a problem. Quick sample of a stack trace as an example - in this case an error happened because CreatedOn date was not set on IAComment entity, however it's impossible to tell from this error/stack trace [SqlTypeException: SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM.] System.Data.SqlTypes.SqlDateTime.FromTimeSpan(TimeSpan value) +2127345 System.Data.SqlTypes.SqlDateTime.FromDateTime(DateTime value) +232 System.Data.SqlClient.MetaType.FromDateTime(DateTime dateTime, Byte cb) +46 System.Data.SqlClient.TdsParser.WriteValue(Object value, MetaType type, Byte scale, Int32 actualLength, Int32 encodingByteSize, Int32 offset, TdsParserStateObject stateObj) +4997789 System.Data.SqlClient.TdsParser.TdsExecuteRPC(_SqlRPC[] rpcArray, Int32 timeout, Boolean inSchema, SqlNotificationRequest notificationRequest, TdsParserStateObject stateObj, Boolean isCommandProc) +6248 System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) +987 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) +162 System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) +32 System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) +141 System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) +12 System.Data.Common.DbCommand.ExecuteReader(CommandBehavior behavior) +10 System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator translator, EntityConnection connection, Dictionary`2 identifierValues, List`1 generatedValues) +8084396 System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) +267 [UpdateException: An error occurred while updating the entries. See the inner exception for details.] System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) +389 System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache) +163 System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) +609 IADAL.IAController.Save(IAHeader head) in C:\Projects\IA\IADAL\IAController.cs:61 IA.IAForm.saveForm(Boolean validate) in C:\Projects\IA\IA\IAForm.aspx.cs:198 IA.IAForm.advance_Click(Object sender, EventArgs e) in C:\Projects\IA\IA\IAForm.aspx.cs:287 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5019

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  • Update primary key value using entity framework

    - by lemkepf
    I'm trying to update one value of a compound primary key from within the entity framework and I'm getting this error: "The property 'CustomerID' is part of the object's key information and cannot be modified. " Here is my code: Dim customer As Customer = (From c In db.Customer Where c.CustomerID = "xxx" AndAlso c.SiteKey = siteKey).FirstOrDefault customer.CustomerID = "fasdfasdf" db.SaveChanges() It seems too simple. Is it true you can't update a primary key within the entity framework? I can't find any documentation on the topic. Thanks!

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  • MvcBuildViews true with Entity Framework in ASP.NET MVC 2

    - by Alper Ozcetin
    Hi everybody, In VS 2010, changing true in a MVC2 project's .csproj file causes an error if you are using Entity Framework. Could not load type 'System.Data.Entity.Design.AspNet.EntityDesignerBuildProvider'. C:\Windows\Microsoft.NET\Framework\v4.0.30319\Config\web.config 129 I want to build views while I'm debugging, and I also want my project compile! Any ideas? Thanks.

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  • Entity Data Model with Oracle

    - by Sridhar
    Hi, I'm using VS 2008 SP1. I want to create an edmx file using my existing database in Oracle 10g. I tried to add ADO.Net Entity Data Model item, but in the Entity Data Model Wizard, .NET Provider for Oracle does not show up. Can someone suggest a way to connect to existing Oracle database to generate the edmx file? Thanks.

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  • Spring.NET and ADO.NET Entity Data Model

    - by Jason
    Having defined an ADO.NET Entity Data Model, I can then instantiate it in a Repository class to query against the database. using (ApplicationEntities ctx = new ApplicationEntities()) { // query, CRUD, etc } However, that particular line of code becomes boilerplate in most of the methods in the repository class. Is it possible to just use Spring.NET to inject the Entity Data Model, either in the class or, even better, in an abstract parent class that all the repositories inherit from?

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  • JPA map relation entity parentID...

    - by Fabio Beoni
    Hello, could someone help me to understand how can I define an entity with JPA mapping that has a relation with it self? For example, my entity is CompanyDivision, divisionA contains divisionB, divisionC and divisionB contains divisionB1, divisionB2 divisionA divisionB divisionB1 divisionB2 divisionC Thank you!

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  • Updating Model with entity collection

    - by jean27
    There are a group of entities named Book and Magazine which inherits from the abstract class PublishedItem. PublishedItem have these properties: ID, Name, Publisher, List of Authors, List of Genres. The Book entity has the ISBN property and the Magazine entity has the ISSN property. I just want to ask how I can update the book's or magazine's list of genres or list of authors?

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  • Asp.net mvc, entity framework, Poco - Architecture

    - by user1576228
    I have a "small" enterprise application, aspnet mvc 3 + entity framework with POCO entity and repository pattern. I structured the solution in 4 projects: POCO entities Domain model Services web application When the application performs a query on the database, use one of the services provided, the service uses the repository and the small classes, as a result I have some dynamic proxy objects that I would like to convert in my domain entities, before using them in mvc views, but I do not know how. Dovrebber be set as the translator? This approach is reasonable?

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  • ASP.NET MVC 2: Linq to SQL entity w/ ForeignKey relationship and Default ModelBinder strangeness

    - by Simon
    Once again I'm having trouble with Linq to Sql and the MVC Model Binder. I have Linq to Sql generated classes, to illustrate them they look similar to this: public class Client { public int ClientID { get; set; } public string Name { get; set; } } public class Site { public int SiteID { get; set; } public string Name { get; set; } } public class User { public int UserID { get; set; } public string Name { get; set; } public int? ClientID { get; set; } public EntityRef<Client> Client { get; set; } public int? SiteID { get; set; } public EntityRef<Site> Site { get; set; } } The 'User' has a relationship with the 'Client' and 'Site . The User class has nullable ClientIDs and SiteIDs because the admin users are not bound to a Client or Site. Now I have a view where a user can edit a 'User' object, the view has fields for all the 'User' properties. When the form is submitted, the appropiate 'Save' action is called in my UserController: public ActionResult Save(User user, FormCollection form) { //form['SiteID'] == 1 //user.SiteID == 1 //form['ClientID'] == 1 //user.ClientID == null } The problem here is that the ClientID is never set, it is always null, even though the value is in the FormCollection. To figure out whats going wrong I set breakpoints for the ClientID and SiteID getters and setters in the Linq to Sql designer generated classes. I noticed the following: SiteID is being set, then ClientID is being set, but then the Client EntityRef property is being set with a null value which in turn is setting the ClientID to null too! I don't know why and what is trying to set the Client property, because the Site property setter is never beeing called, only the Client setter is being called. Manually setting the ClientID from the FormCollection like this: user.ClientID = int.Parse(form["ClientID"].ToString()); throws a 'ForeignKeyReferenceAlreadyHasValueException', because it was already set to null before. The only workaround I have found is to extend the generated partial User class with a custom method: Client = default(EntityRef<Client>) but this is not a satisfying solution. I don't think it should work like this? Please enlighten me someone. So far Linq to Sql is driving me crazy! Best regards

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  • Custom search engine in asp.net mvc and entity framework

    - by Rahat
    Hi, does anyone have any idea how I can get started building a search engine for my asp.net mvc site using entity framework. I plan to build something like: http://www.carsguide.com.au/search/?N=4294962119++492&type=cars there on the left there is a refine search option panel. What's the best approach to design a model for the UI and optimized query with entity framework.

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