Question

Grabbed this from a sample:

protected override ObjectContext CreateDataSource()
    {
        NorthwindContext nw = new NorthwindContext();

        // Configure DbContext before we provide it to the 
        // data services runtime.
        nw.Configuration.ValidateOnSaveEnabled = false;

        // Get the underlying ObjectContext for the DbContext.
        var context = ((IObjectContextAdapter)nw).ObjectContext;

        // Return the underlying context.
        return context;
    }       

Modified it to use the DbContext class that I have in my project.

EDIT: Clarifying that I am casting from a DbContext class just as the sample does:

    public class NorthwindContext : DbContext
{
// Use the constructor to target a specific named connection string
public NorthwindContext()
    : base("name=NorthwindEntities")
{
    // Disable proxy creation as this messes up the data service.
    this.Configuration.ProxyCreationEnabled = false;

    // Create Northwind if it doesn't already exist.
    this.Database.CreateIfNotExists();
}

Running the code gives me an error on the line casting the DbContext:

Unable to cast object of type ‘MyProject.MyDbContext’ to type ‘System.Data.Entity.Infrastructure.IObjectContextAdapter’.

Despite the fact that DbContext implements IObjectContextAdapter:

public class DbContext : IDisposable, IObjectContextAdapter

I’ve found several questions here on SO and other googled sources, but no solutions I have found work.

I’m using Entity Framework 4.2, attempted to update to the 4.3 beta and I’m not sure if that stuck.

Overall goal is to serve data in WCF as a DataService.

Update: Digging deeper I find that there is an ambiguity issue between what my DbContext was (From EntityFramework.dll ) and the type in the WCF project (from Microsoft.data.Entity.CTP)

Not sure how to get what I want from both here….

Answer 1

Just a reminder, the issue here was that an ambiguity between EntityFramework.dll and Microsoft.Data.Entity.CTP was causing the DataInitializer I had for my DbContext to lose functionality.

I solved this issue by replacing my Initializer here:

public class MyDataInitializer : RecreateDatabaseIfModelChanges<MyData>
{
    public void Seed(MyData context)

To:

    public class MyDataInitializer : IDatabaseInitializer<MyData>
{
    public void InitializeDatabase(MyData context)

And I can now access my DataService.

Just one