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  • Entity framework (3.5): How to translate a certain LINQ query to eSQL?

    - by Sebastian P.R. Gingter
    Hi there, I have the following LINQ query that I need to translate to Entity SQL /eSQL): return (ObjectQuery<User>) from user in Users where !user.Roles.Any(r => r.AnIntegerProperty < 0) select user; User.Roles is an navigation property to the n:m relation to Roles and there also is a Role.Users navigation property the other way round. There aren't User_Roles or Roles_User Entities available in the model, and I can't add these. I also can't use the LINQ statement here, because I need to add .OrderBy("it." + propertyname) (comes from another source, can't change that too) later on which is not possible if the ObjectQuery is build with linq. So how do I translate this to eSQL? And where can I find good eSQL samples? I searched for a whole day until now and must admit that eSQL reference is lousy and there aren't any usable examples around the web.

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  • What's all the hype over objectsets in Entity Framework 4?

    - by Kohan
    I am an intermediate user of EF in .net 3.5 and have recently moved to working with .net 4. One thing i keep coming across when reading various tutorials is the use of ObjectSets instead of ObjectQuerys and that they are a great new feature. What is so great about them? Reading this MSDN article titled "Working with ObjectSet (Entity Framework)" It shows two examples on how to add a Product.. one for 3.5 and another for 4.0. http://msdn.microsoft.com/en-us/library/ee473442.aspx Through my lack of knowledge I am possibly bringing up a seperate point here, but i never added a Product like this: //In .NET Framework 3.5 SP1, use the following code: using (AdventureWorksEntities context = new AdventureWorksEntities()) { // Add the new object to the context. context.AddObject("Products", newProduct); } I would have just used context.AddToProducts(newProduct); Please enlighten me. Kind regards, Kohan

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  • How to ask database server for current datetime using entity framework?

    - by Levelbit
    I don't want for my current ModifeidDateTime to be machine time already server time. Every time I want to update or add a person to my datebase on SQL Server 2008 I want to fill ModifiedDateTime filed. It's not like I can change update query as with data adapter command when I work with dataset and to define for my ModifiedDateTime filed to be =GetDate(). I created stored function to retutn me a value of GetDate() method, but I have a problem to import procedure which returns values as int, string ... or no value at all, already just entity values as Person for example in my case. Why is that? Anyway, It would be of great help if you can provide me any solution that works to retrieve DateTime value from server.

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  • How does Hibernate detect dirty state of an entity object?

    - by ???'Lenik
    Is it using some kind of byte codes modification to the original classes? Or, maybe Hibernate get the dirty state by compare the given object with previously persisted version? I'm having a problem with hashCode() and equals() methods for complicated objects. I feel it would be very slow to compute hash code if the object has collection members, and cyclic references are also a problem. If Hibernate won't use hashCode()/equals() to check the dirty state, I guess I should not use equals()/hashCode() for the entity object (not value object), but I'm also afraid if the same operator (==) is not enough. So, the questions are: How does Hibernate know if a property of an object is changed? Do you suggest to override the hashCode()/equals() methods for complicated objects? What if they contains cyclic references? And, also, Would hashCode()/equals() with only the id field be enough?

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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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  • What's the best way to share one Entity Framework 4 data model among multiple applications (meant to

    - by Ivan
    A project (a "solution" to say in VS terms) of mine consists of an ASP.Net 4 Dynamic Data Entities web application, some WinForms applications, some WPF applications, some services. All they are intended to work with one SQL Server database, generated from an Entity Framework 4 model as table-per-type, with lots of inheritance and multiple self-referencing relations. Where do I best put my model? In a separate class library, a copy in every project, in one project, etc. What naming should I best use? Is it good idea to name it MySolution.MyClassLibrary.MySolutionEntities, or just MySolutionEntities or just MySolution? Can you share any useful experience on this subject?

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  • Is there a function similar to Math.Max for Entity Framework?

    - by Ryan ONeill
    I have an entity framework query as follows; From T In Db.MyTable Where (T.Col1 - T.Col2) + T.Col3 - T.Col4 > 0 _ Select T I now need to make sure that the bracketed part '(T.Col1 - T.Col2)' does not go below zero. In .Net, I'd code it as follows (but obviously EF does not like Math.Max). From T In Db.MyTable Where Math.Max(T.Col1 - T.Col2,0) + T.Col3 - T.Col4 > 0 _ Select T Is there an easy way to do this? I am using EF 2.0 (not the latest, just released version). Thanks in advance

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  • C# / Entity Framework / Linq question regarding calling a method when a class is accessed...

    - by Daniel
    So this is probably really basic, but I'm fairly new to all this. I am using Entity Framework with POCO entities. I want to call a method when a class property is set. I am trying to build an advertisement platform. I have a Customer class, a Venue class and an Advertisement class. I have my indexes set up in such a way that I can call customer.venue. However, I want to be able to call Customer.Venue.CurrentAdvertisement and have it execute a method (if CurrentAdvertisement is null) and return the current advertisement. I know I can explicitly set it every time, but I want to be able to override my classes so that whenever the CurrentAdvertisement property is accessed via LINQ it runs that method to return an ad. In order to do this I need to pass the Venue class a variable (venue name).

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  • Can't update rows in my database using Entity Framework...?

    - by Dissonant
    Okay, this is really weird. I made a simple database with a single table, Customer, which has a single column, Name. From the database I auto-generated an ADO.NET Entity Data Model, and I'm trying to add a new Customer to it like so: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Test { class Program { static void Main() { Database1Entities db = new Database1Entities(); Customer c = new Customer(); c.Name = "Harry"; db.AddToCustomer(c); db.SaveChanges(); } } } But it doesn't persist Customer "Harry" to the database! I've been scratching my head for a while now wondering why such a simple operation doesn't work. What on earth could be the problem!?

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  • How do I tell Entity Framework that a column in a view is nullable?

    - by Ryan ONeill
    I have a view which has an Int column which is nullable (let's call it StackOverflowCount). When generating an EF model from the database, the EF designer does not recognise it as nullable and creates the column as an Int. The issue I have is that on the EF designer I have set the column to Nullable and the following error then kills the compilation; Error 3031: Problem in mapping fragments starting at line 2327: Non-nullable column MyView.StackOverflowCount in table MyView is mapped to a nullable entity property. I can get round this by opening the .edmx file in XML mode and manually editing the SQL column definition, but there is no way to do this using the designer and it gets overwritten the next time I refresh from the model from the DB. Is this 'by design' or an example of something that slipped through into EF 4.0? I'm using .Net 4.0 with EF 4.0 under VS 2010.

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  • How do I delete an object from an Entity Framework model without first loading it?

    - by Tomas Lycken
    I am quite sure I've seen the answer to this question somewhere, but as I couldn't find it with a couple of searches on SO or google, I ask it again anyway... In Entity Framework, the only way to delete a data object seems to be MyEntityModel ent = new MyEntityModel(); ent.DeleteObject(theObjectToDelete); ent.SaveChanges(); However, this approach requires the object to be loaded to, in this case, the Controller first, just to delete it. Is there a way to delete a business object referencing only for instance its ID? If there is a smarter way using Linq or Lambda expressions, that is fine too. The main objective, though, is to avoid loading data just to delete it.

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  • Should i use partial classes as business layer when using entity framework?

    - by samsur
    I am working on a project using entity framework. Is it okay to use partial classes of the EF generated classes as the business layer. I am begining to think that this is how EF is intended to be used. I have attempted to use a DTO pattern and soon realized that i am just creating a bunch of mapping classes that is duplicating my effort and also a cause for more maintenance work and an additional layer. I want to use self-tracking-entities and pass the EF entities to all the layers. Please share your thoughts and ideas. Thanks

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  • Is LocalDB supported by Visual Studio 2010 in Entity Framework 5?

    - by Mathias Lykkegaard Lorenzen
    Is LocalDB supported by Visual Studio 2010 in Entity Framework 5, on .NET 4.0? Or am I doing it wrong? I'm getting a "The network path can't be found" issue when instantiating my model container with a connection string for LocalDB. Here's the connection string: var connectionString = "metadata=res://*/Model.csdl|res://*/Model.ssdl|res://*/Model.msl;provider=System.Data.SqlClient;provider connection string=\"data source=(localdb)\v11.0;initial catalog=fablelane_com_db;integrated security=SSPI;multipleactiveresultsets=True;App=EntityFramework\""; Edit 1 I'm receiving the following error when connecting, more specifically: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server). Edit 2 I just figured out that changing to Visual Studio 11 beta doesn't work either. Still receiving the same error-message.

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  • Entity diagram with tables that have foreign keys that point to a non-PK column do not show relation

    - by Jason Coyne
    I have two tables parent and child. If I make a foreign key on child that points to the primary key of parent, and then make an entity diagram, the relationship is shown correctly. If I make the foreign key point to a different column, the relationship is not shown. I have tried adding indexes to the column, but it does not have an effect. The database is sqlite, but I am not sure if that has an effect since its all hidden behind ADO.net. How do I get the relationship to work correctly?

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  • Abstracting entity caching in XNA

    - by Grofit
    I am in a situation where I am writing a framework in XNA and there will be quite a lot of static (ish) content which wont render that often. Now I am trying to take the same sort of approach I would use when doing non game development, where I don't even think about caching until I have finished my application and realise there is a performance problem and then implement a layer of caching over whatever needs it, but wrap it up so nothing is aware its happening. However in XNA the way we would usually cache would be drawing our objects to a texture and invalidating after a change occurs. So if you assume an interface like so: public interface IGameComponent { void Update(TimeSpan elapsedTime); void Render(GraphicsDevice graphicsDevice); } public class ContainerComponent : IGameComponent { public IList<IGameComponent> ChildComponents { get; private set; } // Assume constructor public void Update(TimeSpan elapsedTime) { // Update anything that needs it } public void Render(GraphicsDevice graphicsDevice) { foreach(var component in ChildComponents) { // draw every component } } } Then I was under the assumption that we just draw everything directly to the screen, then when performance becomes an issue we just add a new implementation of the above like so: public class CacheableContainerComponent : IGameComponent { private Texture2D cachedOutput; private bool hasChanged; public IList<IGameComponent> ChildComponents { get; private set; } // Assume constructor public void Update(TimeSpan elapsedTime) { // Update anything that needs it // set hasChanged to true if required } public void Render(GraphicsDevice graphicsDevice) { if(hasChanged) { CacheComponents(graphicsDevice); } // Draw cached output } private void CacheComponents(GraphicsDevice graphicsDevice) { // Clean up existing cache if needed var cachedOutput = new RenderTarget2D(...); graphicsDevice.SetRenderTarget(renderTarget); foreach(var component in ChildComponents) { // draw every component } graphicsDevice.SetRenderTarget(null); } } Now in this example you could inherit, but your Update may become a bit tricky then without changing your base class to alert you if you had changed, but it is up to each scenario to choose if its inheritance/implementation or composition. Also the above implementation will re-cache within the rendering cycle, which may cause performance stutters but its just an example of the scenario... Ignoring those facts as you can see that in this example you could use a cache-able component or a non cache-able one, the rest of the framework needs not know. The problem here is that if lets say this component is drawn mid way through the game rendering, other items will already be within the default drawing buffer, so me doing this would discard them, unless I set it to be persisted, which I hear is a big no no on the Xbox. So is there a way to have my cake and eat it here? One simple solution to this is make an ICacheable interface which exposes a cache method, but then to make any use of this interface you would need the rest of the framework to be cache aware, and check if it can cache, and to then do so. Which then means you are polluting and changing your main implementations to account for and deal with this cache... I am also employing Dependency Injection for alot of high level components so these new cache-able objects would be spat out from that, meaning no where in the actual game would they know they are caching... if that makes sense. Just incase anyone asked how I expected to keep it cache aware when I would need to new up a cachable entity.

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  • Can I use a single DateTime field on the Entity Framework model side when the value is stored in a set of Int fields in the actual database?

    - by Ivan
    The actual table in the database has separate integer fields for storing year, month, day, hour and minute values (all in UTC) (seconds and milliseconds are irrelevant for my task and considered equal to zero). Needless to say it would be of great convenience to have just one field of DateTime type on the application side and hide all the conversion under the cover of the Entity Framework model code. Any directions on how to do that? I am not very experienced with Entity Framework yet.

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  • Core Data - Relationship to dissimilar entities

    - by carotene
    Suppose I have the following data model: Entity Person Attribute name String Attribute personType String Attribute dailyRecords Entity CarpenterDailyRecord Attribute numberOfNailsHammered Int Attribute picNameOfFinishedCabinet String Entity WindowWasherDailyRecord Attribute nameOfBuildingWashed String Attribute numberOfWindowsWashed Int I would like to establish a to-many relationship between the Person.dailyRecords and 1 of the daily record entities (which changes depending on the person type). Of course, i could create a CarpenterPerson and WindowWasher entity which each points to it's unique daily record structure, but i have to group people together in my app somehow. so if i do a Group Entity: Entity Group Attribute people array i'm still stuck. how do i point to multiple & different Person entities? There must be an obvious answer, it's just i'm so new to all of this. thanks!

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  • Which is the good way to update object in EF6

    - by TrieuH
    I have searched and find 2 way to update object in EF var attachedEntity = _context.EntityClasses.Local.First(t => t.Id == entity.Id); //We have it in the context, need to update. if (attachedEntity != null) { var attachedEntry = _context.Entry(attachedEntity); attachedEntry.CurrentValues.SetValues(entity); } else { ////If it's not found locally, we can attach it by setting state to modified. ////This would result in a SQL update statement for all fields ////when SaveChanges is called. var entry = _context.Entry(entity); entry.State = EntityState.Modified; } _context.SaveChanges(); And other way is seem more easy var entity = _context.EntityClasses.FirstOrDefault(t => t.Id == entity.Id); _context.Entry(entity ).EntityState.Modified _context.SaveChanges(); What is best way to update object? NOTE: the performence is importance with me

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  • Blazing fast performance with RadGridView for WPF 4.0 and Entity Framework 4.0

    Just before our upcoming release of Q1 2010 SP1 (early next week), Ive decided to check how RadGridView for WPF will handle complex Entity Framework 4.0 query with almost 2 million records: public class MyDataContext{    IQueryable _Data;    public IQueryable Data    {        get        {            if (_Data == null)            {                var northwindEntities = new NorthwindEntities();                var queryable = from o in northwindEntities.Orders                               from od in northwindEntities.Order_Details                                select new                                {                                    od.OrderID,                                    od.ProductID,                                    od.UnitPrice,                                    od.Quantity,                                    od.Discount,                                    o.CustomerID,                                    o.EmployeeID,                                    o.OrderDate                                };                _Data = queryable.OrderBy(i => i.OrderID);            }             return _Data;        }    }} The grid is bound completely codeless in XAML using RadDataPager with PageSize set to 50: <Window x:Class="WpfApplication1.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation" Title="MainWindow" mc...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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  • Creating an ASP.NET report using Visual Studio 2010 - Part 1

    - by rajbk
    This tutorial walks you through creating an report based on the Northwind sample database. You will add a client report definition file (RDLC), create a dataset for the RDLC, define queries using LINQ to Entities, design the report and add a ReportViewer web control to render the report in a ASP.NET web page. The report will have a chart control. Different results will be generated by changing filter criteria. At the end of the walkthrough, you should have a UI like the following.  From the UI below, a user is able to view the product list and can see a chart with the sum of Unit price for a given category. They can filter by Category and Supplier. The drop downs will auto post back when the selection is changed.  This demo uses Visual Studio 2010 RTM. This post is split into three parts. The last part has the sample code attached. Creating an ASP.NET report using Visual Studio 2010 - Part 2 Creating an ASP.NET report using Visual Studio 2010 - Part 3   Lets start by creating a new ASP.NET empty web application called “NorthwindReports” Creating the Data Access Layer (DAL) Add a web form called index.aspx to the root directory. You do this by right clicking on the NorthwindReports web project and selecting “Add item..” . Create a folder called “DAL”. We will store all our data access methods and any data transfer objects in here.   Right click on the DAL folder and add a ADO.NET Entity data model called Northwind. Select “Generate from database” and click Next. Create a connection to your database containing the Northwind sample database and click Next.   From the table list, select Categories, Products and Suppliers and click next. Our Entity data model gets created and looks like this:    Adding data transfer objects Right click on the DAL folder and add a ProductViewModel. Add the following code. This class contains properties we need to render our report. public class ProductViewModel { public int? ProductID { get; set; } public string ProductName { get; set; } public System.Nullable<decimal> UnitPrice { get; set; } public string CategoryName { get; set; } public int? CategoryID { get; set; } public int? SupplierID { get; set; } public bool Discontinued { get; set; } } Add a SupplierViewModel class. This will be used to render the supplier DropDownlist. public class SupplierViewModel { public string CompanyName { get; set; } public int SupplierID { get; set; } } Add a CategoryViewModel class. public class CategoryViewModel { public string CategoryName { get; set; } public int CategoryID { get; set; } } Create an IProductRepository interface. This will contain the signatures of all the methods we need when accessing the entity model.  This step is not needed but follows the repository pattern. interface IProductRepository { IQueryable<Product> GetProducts(); IQueryable<ProductViewModel> GetProductsProjected(int? supplierID, int? categoryID); IQueryable<SupplierViewModel> GetSuppliers(); IQueryable<CategoryViewModel> GetCategories(); } Create a ProductRepository class that implements the IProductReposity above. The methods available in this class are as follows: GetProducts – returns an IQueryable of all products. GetProductsProjected – returns an IQueryable of ProductViewModel. The method filters all the products based on SupplierId and CategoryId if any. It then projects the result into the ProductViewModel. GetSuppliers() – returns an IQueryable of all suppliers projected into a SupplierViewModel GetCategories() – returns an IQueryable of all categories projected into a CategoryViewModel  public class ProductRepository : IProductRepository { /// <summary> /// IQueryable of all Products /// </summary> /// <returns></returns> public IQueryable<Product> GetProducts() { var dataContext = new NorthwindEntities(); var products = from p in dataContext.Products select p; return products; }   /// <summary> /// IQueryable of Projects projected /// into the ProductViewModel class /// </summary> /// <returns></returns> public IQueryable<ProductViewModel> GetProductsProjected(int? supplierID, int? categoryID) { var projectedProducts = from p in GetProducts() select new ProductViewModel { ProductID = p.ProductID, ProductName = p.ProductName, UnitPrice = p.UnitPrice, CategoryName = p.Category.CategoryName, CategoryID = p.CategoryID, SupplierID = p.SupplierID, Discontinued = p.Discontinued }; // Filter on SupplierID if (supplierID.HasValue) { projectedProducts = projectedProducts.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { projectedProducts = projectedProducts.Where(a => a.CategoryID == categoryID); }   return projectedProducts; }     public IQueryable<SupplierViewModel> GetSuppliers() { var dataContext = new NorthwindEntities(); var suppliers = from s in dataContext.Suppliers select new SupplierViewModel { SupplierID = s.SupplierID, CompanyName = s.CompanyName }; return suppliers; }   public IQueryable<CategoryViewModel> GetCategories() { var dataContext = new NorthwindEntities(); var categories = from c in dataContext.Categories select new CategoryViewModel { CategoryID = c.CategoryID, CategoryName = c.CategoryName }; return categories; } } Your solution explorer should look like the following. Build your project and make sure you don’t get any errors. In the next part, we will see how to create the client report definition file using the Report Wizard.   Creating an ASP.NET report using Visual Studio 2010 - Part 2

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  • EFMVC Migrated to .NET 4.5, Visual Studio 2012, ASP.NET MVC 4 and EF 5 Code First

    - by shiju
    I have just migrated my EFMVC app from .NET 4.0 and ASP.NET MVC 4 RC to .NET 4.5, ASP.NET MVC 4 RTM and Entity Framework 5 Code First. In this release, the EFMVC solution is built with Visual Studio 2012 RTM. The migration process was very smooth and did not made any major changes other than adding simple unit tests with NUnit and Moq. I will add more unit tests on later and will also modify the existing solution. Source Code You can download the source code from http://efmvc.codeplex.com/

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  • Tracking changes in Entity Framework 4.0 using POCO Dynamic Proxies across multiple data contexts.

    - by Rob Packwood
    I started messing with EF 4.0 because I am curious about the POCO possibilities... I wanted to simulate disconnected web environment and wrote the following code to simulate this: Save a test object in the database. Retrieve the test object Dispose of the DataContext associated with the test object I used to retrieve it Update the test object Create a new data context and persist the changes on the test object that are automatically tracked within the DynamicProxy generated against my POCO object. The problem is that when I call dataContext.SaveChanges in the Test method above, the updates are not applied. The testStore entity shows a status of "Modified" when I check its EntityStateTracker, but it is no longer modified when I view it within the new dataContext's Stores property. I would have thought that calling the Attach method on the new dataContext would also bring the object's "Modified" state over, but that appears to not be the case. Is there something I am missing? I am definitely working with self-tracking POCOs using DynamicProxies. private static void SaveTestStore(string storeName = "TestStore") { using (var context = new DataContext()) { Store newStore = context.Stores.CreateObject(); newStore.Name = storeName; context.Stores.AddObject(newStore); context.SaveChanges(); } } private static Store GetStore(string storeName = "TestStore") { using (var context = new DataContext()) { return (from store in context.Stores where store.Name == storeName select store).SingleOrDefault(); } } [Test] public void Test_Store_Update_Using_Different_DataContext() { SaveTestStore(); Store testStore = GetStore(); testStore.Name = "Updated"; using (var dataContext = new DataContext()) { dataContext.Stores.Attach(testStore); dataContext.SaveChanges(SaveOptions.DetectChangesBeforeSave); } Store updatedStore = GetStore("Updated"); Assert.IsNotNull(updatedStore); }

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  • Is it possible to store ObjectContext on the client when using WCF and Entity Framework?

    - by Sergey
    Hello, I have a WCF service which performs CRUD operation on my data model: Add, Get, Update and Delete. And I'm using Entity Framework for my data model. On the other side there is a client application which calls methods of the WCF service. For example I have a Customer class: [DataContract] public class Customer { public Guid CustomerId {get; set;} public string CustomerName {get; set;} } and WCF service defines this method: public void AddCustomer(Customer c) { MyEntities _entities = new MyEntities(); _entities.AddToCustomers(c); _entities.SaveChanges(); } and the client application passes objects to the WCF service: var customer = new Customer(){CustomerId = Guid.NewGuid, CustomerName="SomeName"}; MyService svc = new MyService(); svc.Add(customer); // or svc.Update(customer) for example But when I need to pass a great amount of objects to the WCF it could be a perfomance issue because of I need to create ObjectContext each time when I'm doing Add(), Update(), Get() or Delete(). What I'm thinking on is to keep ObjectContext on the client and pass ObjectContext to the wcf methods as additional parameter. Is it possible to create and keep ObjectContext on the client and don't recreate it for each operation? If it is not, how could speed up the passing of huge amount of data to the wcf service? Sergey

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  • How do I add ROW_NUMBER to a LINQ query or Entity?

    - by Whozumommy
    I'm stumped by this easy data problem. I'm using the Entity framework and have a database of products. My results page returns a paginated list of these products. Right now my results are ordered by the number of sales of each product, so my code looks like this: return Products.OrderByDescending(u => u.Sales.Count()); This returns an IQueryable dataset of my entities, sorted by the number of sales. I want my results page to show the rank of each product (in the dataset). My results should look like this: Page #1 1. Bananas 2. Apples 3. Coffee Page #2 4. Cookies 5. Ice Cream 6. Lettuce I'm expecting that I just want to add a column in my results using the SQL ROW_NUMBER variable...but I don't know how to add this column to my results datatable. My resulting page does contain a foreach loop, but since I'm using a paginated set I'm guessing using that number to fake a ranking number would NOT be the best approach. So my question is, how do I add a ROW_NUMBER column to my query results in this case?

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  • What is the best way in assigning foreign key when using entity framework & LINQ to Entities?

    - by Abdel Olakara
    Hi all, I need to know the best practice of creating an entity object and assigning the foreign key. Here is my scenario. I have a Product table with pid,name,unit_price etc.. I also have a Rating table with pid (foregin key),rate,votes etc... Currently i am doing the following to create the rating object: var prod = entities.Product.First(p => p.product_id == pid); prod.Rating.Load(); if (prod.Rating != null) { log.Info("Rating already exists!"); // set values and Calcuate the score } else { log.Info("New Rating!!!"); Rating rating = new Rating(); // set values and do inital calculation prod.Rating = rating; } entities.SaveChanges(); Even though this works fine, i would like to know the best practice in doing these kind of assignment. Thanks for your suggestions and info. Best Regards, Abdel Olakara

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