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• Entity Framework - An object with the same key already exists in the ObjectStateManager

  - by Justin

  Hey all, I'm trying to update a detached entity in .NET 4 EF: [AcceptVerbs(HttpVerbs.Post)] public ActionResult Save(Developer developer) { developer.UpdateDate = DateTime.Now; if (developer.DeveloperID == 0) {//inserting new developer. DataContext.DeveloperData.Insert(developer); } else {//attaching existing developer. DataContext.DeveloperData.Attach(developer); } //save changes. DataContext.SaveChanges(); //redirect to developer list. return RedirectToAction("Index"); } public static void Attach(Developer developer) { var d = new Developer { DeveloperID = developer.DeveloperID }; db.Developers.Attach(d); db.Developers.ApplyCurrentValues(developer); } However, this gives the following error: An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. Anyone know what I'm missing? Thanks, Justin

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• Deployment Error: Silverlight 4.0 w/WCF RIA Services in ASP.NET MVC 2 App

  - by Dennis Ward

  I've got an MVC 2 App with an RIA Services link to a Silverlight Application. On my local machine, all is well, but when I deploy to Discount ASP servers, neither the MVC controller nor the WCF RIA services called from silverlight function: A silverlight datagrid gets a load error: System.ServiceModel.DomainServices.Client.DomainOperationException: Load operation failed for query... The remote server returned an error NotFound. In the MVC page where I had a simple table that worked prior to adding an EF model and DomainDataSource, I now get the error: Unable to load one or more of the requested types. Retrieve the LoaderExceptions property for more information. This is very similar to an issue I had before, but after upgrading from the betas of WCF/Silverlight 4, but the fix I had added there doesn't seem to work any longer. The link for that issue is: SL4/MVC2/WCF RIA Services = Load Error I'm really struggling with deploying, and could use some help if anybody can shed any light on this. Thanks! Dennis

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• SQL Subquery in LINQ for Entity Framework 4.0

  - by Jorin

  I'm new to LINQ and EF, but I've been able to stumble through for the majority of the queries I have, but this one has me completely confused. No matter what I try, it comes up in SQL Profiler as a big mess :-). I have two tables: Users and UsersProjects. The goal of this query is to list all the users who are working on projects with the specified user. Here is the query as I have it written in SQL. It's a subquery, but I don't know of a way to simplify it further, but I'm open to suggestions there as well. SELECT DISTINCT Users.FirstName, Users.LastName FROM Users INNER JOIN UsersProjects ON Users.ID=UsersProjects.UserID WHERE UsersProjects.ProjectID IN (SELECT ProjectID FROM UsersProjects WHERE UserID=@UserID) Anybody able to help?? It seems like a fairly simple subquery in SQL, but in LINQ, I'm baffled. Thanks, Jorin

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• How to update model in the database, from asp.net MVC2, using Entity Framework?

  - by Eedoh

  Hello. I'm building ASP.NET MVC2 application, and using Entity Framework as ORM. I am having troubles updating object in the database. Every time I try entity.SaveChanges(), EF inserts new line in the table, regardless of do I want update, or insert to be done. I tried attaching (like in this next example) object to entity, but then I got {"An object with a null EntityKey value cannot be attached to an object context."} Here's my simple function for inserts and updates (it's not really about vehicles, but it's simpler to explain like this, although I don't think that this effects answers at all)... public static void InsertOrUpdateCar(this Vehicles entity, Cars car) { if (car.Id == 0 || car.Id == null) { entity.Cars.AddObject(car); } else { entity.Attach(car); } entitet.SaveChanges(); } I even tried using AttachTo("Cars", car), but I got the same exception. Anyone has experience with this?

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• Repository Pattern with Entity Framework 3.5 and MVVM

  - by Ravi

  I am developing a Database File System. I am using - .Net framework 3.5 Entity Framework 3.5 WPF with MVVM pattern The project spans across multiple assemblies each using same model. One assembly,let's call it a "server", only adds data to the database using EF i.e. same model.Other assemblies (including the UI) both reads and writes the data.The changes made by server should immediately reflect in other assemblies. The database contains self referencing tables where each entity can have single OR no parent and (may be) some children. I want to use repository pattern which can also provide some mechanism to handle this hierarchical nature. I have already done reading on this on Code Project. It shares the same context(entities) everywhere. My question is - Should I share the same context everywhere? What are the advantages and disadvantages of doing that?

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• Entity Framework - Using Transactions or SaveChanges(false) and AcceptAllChanges()?

  - by mark smith

  Hi there, I have been investigating transactions and it appears that they take call of them selves in EF as long as i pass false to savechanges.. SaveChanges(false) and if all goes well then AcceptAllChanges() Question is what is something goes bad, don't have to rollback? or as soon as the my method goes out of scope its ended? What happens to any indentiy columns that were assigned half way through the transaction.. i presume if somebody else added a record after mine before mine went bad then this means there will be a missing Identity value. Is there any reason to use standard "transactionScope" in code? ideas? - thanks

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• Unique Keys not recognized by Entity Framework

  - by David Pfeffer

  I have two tables, Reports and Visualizations. Reports has a field, VisualizationID, which points to Visualization's field of the same name via a foreign key. It also has a unique key declared on the field. VisualizationID is not nullable. This means the relationship has to be 0..1 to 1, because every Reports record must have a unique, not null Visualizations record associated with it. The Entity Framework doesn't see it this way. I'm getting the following error: Error 113: Multiplicity is not valid in Role 'Report' in relationship 'FK_Reports_Visualizations'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be *. What's the problem here? How can I make the EF recognize the proper relationship multiplicity?

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• Repository Pattern with Entity Framework 3.5

  - by Ravi

  I am developing a Database File System. I am using - .Net framework 3.5 Entity Framework 3.5 WPF with MVVM pattern The project spans across multiple assemblies each using same model. One assembly,let's call it a "server", only adds data to the database using EF i.e. same model.Other assemblies (including the UI) both reads and writes the data.The changes made by server should immediately reflect in other assemblies. The database contains self referencing tables where each entity can have single OR no parent and (may be) some children. I want to use repository pattern which can also provide some mechanism to handle this hierarchical nature. I have already done reading on this on Code Project. It shares the same context(entities) everywhere. My question is - Should I share the same context everywhere? What are the advantages and disadvantages of doing that?

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• Repository Pattern with Entity Framework 3.5

  - by Ravi

  I am developing a Database File System. I am using - .Net framework 3.5 Entity Framework 3.5 WPF with MVVM pattern The project spans across multiple assemblies each using same model. One assembly,let's call it a "server", only adds data to the database using EF i.e. same model.Other assemblies (including the UI) both reads and writes the data.The changes made by server should immediately reflect in other assemblies. The database contains self referencing tables where each entity can have single OR no parent and (may be) some children. I want to use repository pattern which can also provide some mechanism to handle this hierarchical nature. I have already done reading on this on Code Project. It shares the same context(entities) everywhere. My question is - Should I share the same context everywhere? What are the advantages and disadvantages of doing that?

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• Entity framework createquery question.

  - by Tony Heflin

  I am trying to create a generic search form to use in an EF app. I want to be ably to specify the entity to query at runtime below is a simplified version of the code. cx is the contect object, valuelists is the entity in question. 1: Dim q As String = "select c from intactentities.valuelists as c" 2: Dim x = cx.CreateQuery(Of ValueLists)(q) 3: TextBox1.Text = x.Count This works but I need to remove the hardcoded reference to valuelists in line 3. I expect I am overlooking something simple can anyone suggest a simple solution? Thanks Tony

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• SQL's Rownumber with Linq-to-entities

  - by mariki

  I am converting my project to use EF and also want to covert stored procedures into Linq-to-entities queries. This my SQL query (simple version) that I have trouble to convert: SELECT CategoryID, Title as CategoryTitle,Description, LastProductTitle,LastProductAddedDate FROM ( SELECT C.CategoryID, C.Title,C.Description, C.Section, P.Title as LastProductTitle, P.AddedDate as LastProductAddedDate, ROW_NUMBER() OVER (PARTITION BY P.CategoryID ORDER BY P.AddedDate DESC) AS Num FROM Categories C LEFT JOIN Products P ON P.CategoryID = C.CategoryID ) OuterSelect WHERE OuterSelect.Num = 1 In words: I want to return all Categories (from Categories table) and title and date of addition of the product (from Products table) that was added last to this category. How can I achieve this using Entity frame work query? In most efficient way.

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• Force WPF to Commit Changes on Focused Element

  - by John L.

  I'm working with VS2010, WPF and EF. I've placed controls on my window by dragging an entity out of the Data Sources toolwindow. I used the "details" setting so my entity is represented by several labels and textboxes. I've also added a button with the following code: _context.SaveChanges(); When I'm editing data, the changes in whichever textbox has focus are not committed back to the DB. Everything else commits just fine. If I shift focus to another element prior to hitting the save button, it commits as well. I've experienced the same thing with the DataGrid. I know I'm missing something simple, but I can figure it out. Any ideas on what I'm missing? Thanks!

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• Entity Framework and consuming a WCF service

  - by nakori

  I'm getting data where the database is hidden behind a WCF service. Is it possible to use Entity Framework in a scenario where I have custom objects coming from a web service? (No access to the external database, and no current plans for insert/update/delete logic) Starting with an empty EF model and adding an entity I get this error on compile: No mapping specified for instances of the EntitySet and AssociationSet in the EntityContainer .. Is it possible to make an entity this way, and fill it with data received from an object? (In this case a WCF, but could also be a predefined model class/xml data) If the web service retured a Customer object I could do something like this with a dataset: Make an unbound table and do a loop through the customer properties adding them to a temp row, add it with tbl_Customer.Addtbl_CustomerRow(customerRow) to get my view filled. thanks, nakori

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• Calling Entity Framework function import from code

  - by Mikey Cee

  So I have a stored procedure called Spr_EventLogCreate defined in my database. I have created a function import in my data model called LogEvent with no return type, and I can see this function in the Model Browser tree at MyModel.edmx MyModel EntityContainer Function Imports LogEvent. I thought I should then be able to call the function in my code as follows: var context = new MyModelEntities(); context.LogEvent(...); But the LogEvent() method is not present. I must be being really stupid here, but how do I call my imported function? Using VS 2008 and EF 3.5.

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• Entity Framework 4 relationship management in POCO Templates - More lazy than FixupCollection?

  - by Joe Wood

  I've been taking a look at EF4 POCO templates in beta 2. The FixupCollection looks fine for maintaining the model correctness after updating the relationship collection property (i.e. product.Orders it would set the order.Product reference ). But what about support for handling the scenario when some of those Order objects are removed from the context? The use-case of maintaining cascading deletes in the in-memory model. The old Typed DataSet model used to do this by performing the query through the container to derive the relationship results. Like the DataSet, this would require a reference to the ObjectContext inside the entity class so that it could query the top-level Order collection. Better support for Separation of Concerns in the ObjectContext would be required. It looks like EF is not suited to this use-case that DataSets did out of the box.... am I right?

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• Best Practices - Data Annotations vs OnChanging in Entity Framework 4

  - by jptacek

  I was wondering what the general recommendation is for Entity Framework in terms of data validation. I am relatively new to EF, but it appears there are two main approaches to data validation. The first is to create a partial class for the model, and then perform data validations and update a rule violation collection of some sort. This is outlined at http://msdn.microsoft.com/en-us/library/cc716747.aspx The other is to use data annotations and then have the annotations perform data validation. Scott Guthrie explains this on his blog at http://weblogs.asp.net/scottgu/archive/2010/01/15/asp-net-mvc-2-model-validation.aspx. I was wondering what the benefits are of one over the other. It seems the data annotations would be the preferred mechanism, especially as you move to RIA Services, but I want to ensure I am not missing something. Of course, nothing precludes using both of them together. Thanks John

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• Is writing eSQL database agnostic?

  - by Robert Koritnik

  Using EF we can use LINQ to read data which is rather simple (especialy using fluent calls), but we have less control unless we write eSQL on our own. Is writing eSQL database actually data store independant code? So if we decide to change data store, can the same statements still be used? Is writing eSQL strings in your code pose any serious security threats similar to writing TSQL statements in plain strings? So we moved to SPs. Could we still mode eSQL scripts outside of code as well and use some other technique to make them a bit more secure?

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• IEditableCollectionView.AddNew() Throwing ArgumentNullException

  - by Eugarps

  In the context of Silverlight RIA using DomainContext and, the code as follows: private void AddProductButton_Click(object sender, RoutedEventArgs e) { var target = (Web.LocatorProduct)((IEditableCollectionView)ProductSource.DataView).AddNew(); target.Locator = LocatorID; target.Product = NewProduct.Text.ToUpper(); ((IEditableCollectionView)ProductSource.DataView).CommitNew(); } Is throwing ArgumentNullException in AddNew(), CreateIdentity() further up on the stack (a generated method) due to product being null. Product and LocatorID are, in combination, the primary key. I'm guessing that EF is not allowing me to generate a new item without meeting database contraints? How does this make sense if I need to obtain a primary key from the user? I have control over all tiers of the application, so suggestions on database design if needed are also welcomed.

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• EF4, MVC 3, Azure and Code First or Traditional

  - by RichardAlanA

  I am planning to build a web application using ASP MVC3 that runs on Azure with a SQL Azure back end. I would like to use the Microsoft stack and have no plans to ever change to another stack. I am looking into the use of WCF and WF but that would be in the future. I looked at the traditional and Code First approach to using Entity Framework but I can't see if there is any advantage in using one or the other approach. Sure they each have advantages but for me I don't care if my classes do inherit from EF classes. All I want is to find the most efficient solution. Can anyone out there give me some advice as to which approach might be the best. thanks very much Richard

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• Binding custom property in Entity Framework

  - by deverop

  I have an employee entity in my EF model. I then added a class to the project to add a custom property public partial class Employee { public string Name { get { return string.Format("{0} {1}", this.FirstName, this.LastName); } } } On a aspx form (inside a FormView), I want to bind a DropDownList to the employee collection: <asp:Label runat="server" AssociatedControlID="ddlManagerId" Text="ManagerId" /> <asp:DropDownList ID="ddlManagerId" runat="server" DataSourceID="edsManagerId" DataValueField="Id" DataTextField="Name" AppendDataBoundItems="true" SelectedValue='<%# Bind("ManagerId") %>'> <asp:ListItem Text="-- Select --" Value="0" /> </asp:DropDownList> <asp:EntityDataSource ID="edsManagerId" runat="server" ConnectionString="name=Entities" DefaultContainerName="Entities" EntitySetName="Employees" EntityTypeFilter="Employee" EnableFlattening="true"> </asp:EntityDataSource> Unfortunately, when I fire up the page, I get an error: DataBinding: 'System.Web.UI.WebControls.EntityDataSourceWrapper' does not contain a property with the name 'Name'. Any ideas what I'm doing wrong?

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• ADO.NET Known Issues?

  - by Israel Rodriguez

  So, I'm starting a new Project in my company, and it's kinda big. We are going to use .NET 3.5, and I wish to known if there are any know bugs or perfomance issues that could give weird behaviour for my project? I'm reading some things about EFv4 and all they say is that EFv3.5 have too many problems. After all, what's the best and fastest way, ADO.NET Entities or extract the data from my DB directly to a DataReader? The EF Oracle provider is stable? The project will be .NET 3.5 and Oracle.

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• In separate data access & business logic layer, can I use Entity framework classes in business layer

  - by Greg

  In separate data access & business logic layer, can I use Entity framework classes in business layer? EDIT: I don't think I will need to swap out the data access layer from my business logic in the future (i.e. will be SQL Server), however I will for the UI layer. Therefore the question is more meant to be are there any major issues with using EF classes for me in the business layer? Seems like there would be less plumbing code.

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• Properties in partial class not appearing in Data Sources window!

  - by Tim Murphy

  Entity Framework has created the required partial classes. I can add these partial classes to the Data Sources window and the properties display as expected. However, if I extend any of the classes in a separate source file these properties do not appear in the Data Sources window even after a build and refresh. All properties in partial classes across source files work as expected in the Data Sources window except when the partial class has been created with EF. EDIT: After removing the offending table for edm designer, adding back in it all works are expected. Hardly a long term solution. Anyone else come across a similar problem?

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• POX return data from WCF Data Services

  - by keithwarren7

  I am using WCF Data Services (netfx4) to provide data sourced from SQL via EF, the standard OData mechanism is fine and JSON works as well but I need a third option for generic POX (plain old xml). I have yet to come across a simple strategy or switch that allows me to control this but I am sure one must exist or a workaround method might be available. Any ideas? Ideally I would like to be able to use something like the JSONP option wherein I append 'format=JSON' to the URL, in this case 'format=pox' or 'POX=true' or something of that nature.

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• Correct way to edit and update complex viewmodel objects using asp.net-mvc2 and entity framework

  - by jslatts

  I have a table in my database with a one to many relationship to another table: ParentObject ID Name Description ChildObject ID Name Description ParentObjectID AnotherObjectID The objects are mapped into Entity Framework and exposed through a data access class. It seemed like ViewModels are recommended when the data to be displayed greatly differs from the domain object, so I created a ViewModel as follows: public class ViewModel { public IList<ParentObject> ParentObjects { get; set; } public ParentObject selectedObject { get; set; } public IList<ChildObject> ChildObjects { get; set; } } I have a view that displays a list of ParentObjects and when clicked will allow a ChildObject to be modified saved. <% using (Html.BeginForm()) { %> <table> <% foreach (var parent in Model.ParentObjects) { %> <tr> <td> ObjectID [<%= Html.Encode(parent.ID)%>] </td> <td> <%= Html.Encode(parent.Name)%> </td> <td> <%= Html.Encode(parent.Description)%> </td> </tr> <% } %> </table> <% if (Model.ParentObject != null) { %> <div> Name:<br /> <%= Html.TextBoxFor(model => model.ParentObject.Name) %> <%= Html.ValidationMessageFor(model => model.ParentObject.Name, "*")%> </div> <div> Description:<br /> <%= Html.TextBoxFor(model => model.ParentObject.Description) %> <%= Html.ValidationMessageFor(model => model.ParentObject.Description, "*")%> </div> <div> Child Objects </div> <% for (int i = 0; i < Model.ParentObject.ChildObjects.Count(); i++) { %> <div> <%= Html.DisplayTextFor(sd => sd.ChildObjects[i].Name) %> </div> <div> <%= Html.HiddenFor(sd => sd.ChildObjects[i].ID )%> <%= Html.TextBoxFor( sd => sd.ChildObjects[i].Description) %> <%= Html.ValidationMessageFor(sd => sd.ChildObjects[i].Description, "*") %> </div> <% } } } %> This all works fine. My question is around the best way to update the EF objects and persist the changes back to the database. I initially tried: [HttpPost] public ActionResult Edit(ViewModel viewModel) { ParentObject parent = myRepository.GetParentObjectByID(viewModel.SelectedObject.ID); if ((!ModelState.IsValid) || !TryUpdateModel(parent, "SelectedObject", new[] { "Name", "Description" })) { || !TryUpdateModel(parent.ChildObjects, "ChildObjects", new[] { "Name", "Description" })) { //Code to handle failure and return the current model snipped return View(viewModel); } myRepository.Save(); return RedirectToAction("Edit"); } When I try to save a change to the child object, I get this exception: Entities in 'MyEntities.ChildObject' participate in the 'FK_ChildObject_AnotherObject' relationship. 0 related 'AnotherObject' were found. 1 'AnotherObject' is expected. Investigation on StackOverflow and generally googling led me to this blog post that seems to describe my problem: TryUpdateModel() does not correctly handle nested collections. Apparently, (and stepping through the debugger confirms this) it creates a new ChildObject instead of associating with the EF objects from my instantiated context. My hacky work around is this: if (viewModel.ChildObjects.Count > 0) { foreach (ChildObject modelChildObject in viewModel.ChildObjects) { ChildObject childToUpdate = ParentObject.ChildObject.Where(a => a.ID == modelChildObject.ID).First(); childToUpdate.Name = modelChildObject.Name; } } This seems to work fine. My question to you good folks: Is there correct way to do this? I tried following the suggestion for making a custom model binder per the blog link I posted above but it didn't work (there was an issue with reflection) and I needed to get something going ASAP. PS - I tried to cleanup the code to hide specific information, so beware I may have hosed something up. I mainly just want to know if other people have solved this problem. Thanks!

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