Meta-Me

UPDATE 2 @1:21 pm on 16th August (PST): There is an updated version of the nuget package that resolves the previous dependency issues. Oh and my comments are now working again. UPDATE 1 @10:00 am on 16th August (PST): If you’ve tried using the...

As of right now Enums are not in EF4. Now we will be listening to your feedback about Beta1, and making some adjustments, so you never know, but at the moment it doesn’t look like they will be supported. Yesterday though I came up with a workaround...

Since my last set of blog posts on OData support in WebAPI (see parts 1 & 2 ) we’ve been busy adding support for Server Driven Paging, Inheritance and OData Actions. Our latest alpha release on Nuget has preview level support for these features. Lets...

Imagine if you have a table of People and you want to retrieve only those whose the Firstname is in a list of interesting firstnames. This is trivial in SQL, you write something like this: SELECT * FROM People WHERE Firstname IN ('Alex', 'Colin', ...

Hopefully if you're reading this you've noticed that I've started a series of Tips recently. The tips will mostly apply to Entity Framework or Data Services. Seeing as I expect to have a lots of tips, it probably makes sense to have some sort of...

Background If you've been reading the EF Design Blog you will have seen that we recently announced something called " FK Associations " for the EF in .NET 4.0. However in .NET 3.5 SP1, we only support Independent Associations. What that means is that...

This is 22nd post in my ongoing series of Entity Framework Tips . If you want to do eager loading with the Entity Framework it is generally really easy, you simply write something like this: var results = from post in ctx.Posts.Include(“Comments”)...

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...

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...

Next week we will release an official RC of the Microsoft ASP.NET WebAPI OData assembly. This marks the third release on our way to RTM.  Although this post talks about code that hasn’t been officially release yet, since all development is happening...

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...

Problem The most common way to delete an Entity in the Entity Framework is to pull the Entity you want to delete into the context and then delete it like this: // Find a category by ID by // TRIVIA: in .NET 4.0 you can use .Single() // which will throw...

So earlier today I was lamenting that an anonymous type can't be shared between functions with Wes Dyer , when he said "Well actually they can..." Cue me learning something cool. The first step is to create a seemingly innocent method: public...

Imagine if you have these 3 methods: public Employee GetEmployee(string alias); public Department GetDepartment(Employee employee); public Employee GetManager(Department department); Now imagine if you want to find the Manager of the Department that some...

Introduction Data Services sits above a Data Service Provider, which is responsible for interacting with the underlying Data Source on behalf of the Data Service. Data Services ships with some internal providers, and makes it possible for you to...

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....

What strategies does the Entity Framework support? The Entity Framework supports 3 primary inheritance strategies: Table Per Hierarchy (TPH): In TPH, all data for a type hierarchy is stored in one table, and there is a discriminator column that is used...

The Problem: In some of earlier tips we talked about using Attach to load things into the ObjectContext in the unchanged state without wearing the cost of doing a query. Attach is the weapon of choice if performance is your goal. Unfortunately our APIs...

Scenario: In order to make applications perform it makes a lot of sense to cache commonly used reference data. Good examples of reference data include things like States, Countries, Departments etc. Generally you want to have this data readily at hand...

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...

One of the most common questions we get is how long should an ObjectContext should live. Options often cited include one per: Function Form Thread Application Plenty of people are asking these types of questions, case in point here is a question on Stackflow...

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...

Whenever I find myself implementing a series of interfaces to plug into a framework or server, I always find myself wondering how the server will call my implementations. For me this is about forming a mental model to simplify how I think about what...

So if you've been reading the Entity Framework Design Blog you will have heard us talk about T4 . It is a technology that ships with Visual Studio 2008 (and 2005 as a separate download). In .NET 4.0 the Entity Framework is leverage T4 to help with...

Those of you who know what I am talking about will probably also know that we have been saying publicly that the Entity Framework doesn't support them. Now for those who don't know what an association with a payload is, imagine something like: Order...