Now that we’ve defined our two POCO model classes, let’s create a class that we can use to handle the retrieval/persistence of Dinner and RSVP instances from a database. 

We’ll name this class “NerdDinners”. It derives from the DbContext base class, and publishes two public properties – one that exposes our Dinner objects, and one that exposes our RSVP objects:

The DbContext and DbSet classes used above are provided as part of the EF4 Code-First library.  You’ll need to add a reference to the System.Data.Entity.CTP assembly that is installed into the \Program Files\Microsoft ADO.NET Entity Framework Feature CTP4\Binaries directory to reference these classes.  You’ll also want to add a “using System.Data.Entity” namespace statement at the top of your “NerdDinners” class file.

That is all the code we need to write

The above three classes contain all of the code necessary to implement a basic model and data persistence layer for our NerdDinner application.  We do not need to configure any additional database schema mapping information, nor run any tools, nor edit any XML files, nor use any designers in order to start using our classes to retrieve, update, and save data into a database.