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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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The normal way that you create an ADO.NET Data Services (aka Astoria) Service is by creating a class that derives from DataService<T>. public class BloggingService : DataService<BloggingEntities> And if you want to use Entity Framework under
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Problem Someone asked how to do a Conditional Include a couple of days ago on StackOverflow. They wanted to query for some entity (lets say Movies) and eager load some related items (lets say Reviews) but only if the reviews match some criteria (i.e.
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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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Imagine that in your database you have a cascade delete on an FK relationship. Something like this: Here the Delete Rule says that when a Category is deleted all the related Products should be deleted too. If you generate an EF model from this database
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We recently released a CTP that extends EF 4 Beta 1 which included Code Only. You can read more about Code Only here , here and here . If you look at the walkthroughs for Code Only you will see code that looks something like this: // Create a builder
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Imagine you want to write a query like this: var possibleBuyers= from p in ctx.People where p.Address.City == “Sammamish” && InMarketForAHouse(p) select p; Now theoretically this is possible so long as there is a SQL translation for InMarketForAHouse.
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Imagine you have a database function like the DistanceBetween function in Nerd Dinner : CREATE FUNCTION [dbo].[DistanceBetween]( @Lat1 as real, @Long1 as real, @Lat2 as real, @Long2 as real) RETURNS real AS BEGIN … END And you want to use it with the
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Here’s a scenario which Damien and I encountered recently. We needed a way of specifying Facets for properties on Entities, i.e. things like Nullable , MaxLength , Precision etc. And we needed a class hierarchy because different types of properties have
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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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