Question

I have a large MVVM-type solution which I originally wrote using VS2010 Express with .NET4. The Model uses Entities to access a SQL Server 2012 database.

I managed to lose the Model project recently, which didn’t seem a big deal, as it really consists of the Auto-generated Entities with a few minor modifications. I have therefore recreated the model project using VS2012 with .NET4.5 and EF5. I have upgraded the ViewModel to .NET4.5 and have imported EntityFramework using the package manager.

The problem is, my ViewModel (a separate Class Library) throws several compile-time errors which I cannot figure out. These revolve around:

1. The main Entities class (in my case, CN2Entities) no longer has a constuctor which takes a connection string. This is confirmed by autocomplete, which only offers a parameterless constructor.

2. The individual database object classes which map to database tables, such as “Addresses” no longer contain their static members. For example:

   address_ = Address.CreateAddress(-1);

This code used to provide me with a nice, empty address record to fill and add to the database. This is no longer valid. In fact, the only static members of the Address class appear to be “Equals” and “ReferenceEquals”.

1. The main Entities class no longer contains the AddToAddress(Address) function, which would then take the new Address object (representing a row of the Addresses table) and add it to the database. I would then call Entities.SaveChanges() to commit the addition. This function still seems to be present.

Can anyone please help me with what is going on? Is this something to do with the new way EF5 works or do I have a corrupted solution which is not providing me with the correct references?

Answer 1

Whey you recreated the model project you have used Entity Framework 5 with completely different API (and different auto-generating strategy). There are two APIs for EF since EF 4.1 but in VS 2010 second API (DbContext API) was optional and available only after referencing separate assembly. In VS 2012 DbContext API is supposed as default when you add EDMX (VS downloads that additional assembly from NuGet).

You can still use old API – expand EDMX file in solution explorer and delete all files with .tt extension. After that open EDMX diagram and in properties change Code Generation Strategy from None to Default and save the diagram. It should generate classes for the old API but I don’t know if the code generator is the same as it used to be in VS 2010.