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UPDATE: I’ve made a few updates to the code / write-up to reflect refactors I’ve made as I’ve implemented more of the interfaces. This is Part 3 of my ongoing series on Creating a Data Service Provider , and in this post we’ll look at how to implement...

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...

To create a read-only Data Service Provider (or DSP) you need to implement two Data Services interfaces: IDataServiceMetadataProvider to provide the metadata and IDataServiceQueryProvider to handle the queries. But first Data Services needs a way to...

One of the the coolest things about Data Services is its provider model. Any data-source can be exposed as an OData Data Service simply by implementing a few interfaces. SharePoint 2010 implements these interfaces to expose list data, and you can too...

I’ve been playing around with creating a custom Astoria Data Service Provider , aka DSP, for a while now. So far I’d managed to get my metadata all setup, so browsing to $metadata works great. I’d got a few simple queries work. Basically everything was...

Every wonder if you can host an Astoria Data Service in WCF? Well turns out the answer is yes, in fact once you’ve got your references set up etc it is pretty easy. Step 1 – Setting up your project Here is what my working project looks like: In this example...

Problem: Take this code: Category oldCategory = ctx.Categories .Include("Products") .First(c => c.Name == "Drink"); Category newCategory = new Category {Name = "Beverage"}; foreach(Product product in oldCategory.Products) { newCategory.Products...

This time a real simple one prompted by this question on StackOverflow. Problem: If you tell the Entity Framework about this class using Code-Only, by default every property becomes part of Entity, and as a result stored in the database. Usually this...

Background By default the Entity Framework embeds its metadata inside your assembly as a resource. It also puts a connection string in the App or Web Config that references those resources something like this: <add name="BloggingEntities" connectionString...

I recently did a crash course in Data Services and OData . While doing so I realized my notes might be useful for you guys. So here is my little cheat sheet to quickly get up to speed with OData Urls. Note: OData Services may not necessarily support all...

Problem: When writing code against a Data Service, like say SharePoint , the client application must provide a valid set of credentials, or you will see a dreaded “401 Unathorized” response. For Silverlight applications hosted on the same site as...

Daniel Wertheim left a couple of comments on Tip 42 , that point to a series of posts he has written about using Code-Only to write clean code. The series is really interesting as he delves into topics like: facades, relationships between non-public...

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...

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...

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 ...

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;...

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...

There have been lots of posts on the EFDesign blog talking about how the features in Code Only have evolved. But very little covering what we think will be the best way to write the code. You may have seen code like this: var prodConf = builder.Entity<Product>...

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....

I had an interesting in passing conversation with someone today about tagging file systems… which reminded me of my own sordid past. Before I joined Microsoft, before I was an MVP, before I released Base4, I wrote something called XTend. At the time I...

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...

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...

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...

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...

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...