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Background: When we give examples of how to use Code-Only we always start with a strongly typed Context derived from ObjectContext . This class is used to bootstrap the model. For example this (property bodies omitted for simplicity sake): public class
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Sometimes you’ll find you need to issue a query or command that the Entity Framework can’t support. In fact this problem is common to most ORMs, which is why so many of them have a backdoor to the database. The Entity Framework has a backdoor too… .NET
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Problem: Imagine that you have these entities public class Product { public int ID { get; set; } public string Name { get; set; } public virtual Category Category { get; set; } } public class Category { public int ID { get; set; } public string Name {
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Scenario: In EF 4 we have FK relationships , available for the first time in .NET 4.0 Beta 2, so it is now possible to have a model something like this: public class Division { public int DivisionID {get;set} // Primary Key public string Name {get;set;}
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While writing my tips series and writing EF controllers for MVC I found that I regularly wanted to create and attach a stub entity . Unfortunately it isn’t quite that simple, you have to make sure the entity isn’t already attached first, otherwise you’ll
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If you write a LINQ to Entities query like this: var results = from c in ctx.Vehicles.OfType<Car>() select c; It will bring back, Cars and any type that derives from Car, like say SportCar or SUV. If you just want Cars and you don’t want derived
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UPDATE: thanks Zeeshan for pointing out that by default only non-nullable columns end up in the key for view backed entities. Imagine this situation, you have a view in your database, and it is updatable. Next you decide to use this view with the Entity
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If you have code that looks like this: var results = from c in ctx.Customers where c.SalesPerson.EmailAddress == “…” select c; foreach(var customer in results) { Console.WriteLine(customer.Name); if (IsInteresting(customer)) { customer.Orders.Load();
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Background: Over the last 2 years lots of people have complained about the way Eager loading works in the Entity Framework, or rather the way you ask the Entity Framework to eagerly load. Here is how you do it: var results = from b in ctx.Blogs.Include(“Posts”)
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What are Stub Entities? A stub entity is a partially populated entity that stands in for the real thing. For example this: Category c = new Category {ID = 5}; is a stub entity. It has only the ID populated, which indicates this is a stub for Category
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For well over a year now I've been talking about how it is possible with EF to write a provider that sits between the EF and the native database provider. There are lots of reasons why you might do this. Here are some examples, you could write a: Tracing
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Sometimes rather than writing this: var customer = ctx.Customers.First(c => c.ID == 5); You would rather write something like this: var customer = ctx.Customers.GetCustomerById(5); In .NET 4.0 this would be trivial to do by modifying the T4 templates
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Customers often ask how to get from an Entity back to the ObjectContext . Now generally we don’t recommend trying this. But sometimes you really need a way to get to the ObjectContext . For example if you are in method and all you have is the Entity,
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This is 21st post in my ongoing series of Entity Framework Tips , and the first that is specific to EF 4.0. Entity Framework 4.0 Beta 1 As you’ve probably heard VS 2010 Beta 1 is now available to subscribers which means some of you can get your hands
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This is 20th post in my ongoing series of Entity Framework Tips . Fixed Length Field Padding: If you have an fixed length column in the database, for example something like NCHAR(10) when you do an insert, padding happens automatically. So for example
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