How to configure ProviderManifestToken for EF Code First

Question

I have a asp.net MVC3 project using EF code-first. For my unit testing I have been using SQL Server CE 4.0 and SQL Server 2008 Express. Both have worked perfectly with EF ge

Answer 1

In my case, my connection string name must match the context class name.

Connection String:

<connectionStrings>
  <add name="NunuContext" connectionString="Data Source=|DataDirectory|Nunu.sdf" providerName="System.Data.SqlServerCe.4.0" />
</connectionStrings>

Context Class:

using System.Data.Entity;
namespace Nunu.Models
{
    public class NunuContext : DbContext
    {
        System.Data.Entity.DropCreateDatabaseIfModelChanges<Nunu.Models.NunuContext>());

        public DbSet<Nunu.Models.NunuFirst> NunuFirsts { get; set; }

        public DbSet<Nunu.Models.NunuLast> NunuLasts { get; set; }
    }
}

Answer 2

I found, when i provided explicit "User Id=abcUser; Password=somePwd;" in my connection string i am able to resolve the same error. Earlier i was using the "Trusted_Connection=true;", which allowed me to debug my web project, but started giving me error - {"The provider did not return a ProviderManifestToken string."} as soon as i added the Windows azure project and tried debugging the Azure project after adding my web project as a web role under it.

Hope it helps some one experiencing a similar situation.

Thanks, Vivek Bahl

Answer 3

After hours of searching & fiddling, I found a way to do it. Turns out the DbModelBuilder class takes a DbProviderInfo in its Build method, so I use that instead of relying on EF to call OnModelCreated:

// 'Entities' is my DbContext subclass, the "container" in EF terms.
public static Entities GetNewContext()
{
    // Get a connection, for example:
    var connection = new SqlConnection(GetConnectionString());

    // Create a DbModelBuilder
    var modelBuilder = new DbModelBuilder();
    // Configure the model builder.
    // I changed my DbContext subclass - added a public version of OnModelCreated and called it ConfigureModelBuilder
    Entities.ConfigureModelBuilder(modelBuilder);

    // Here's where the magic happens.
    // Build the model and pass the ProviderManifestToken (I use 2005 to avoid a bug in precision of sql datetime columns when using concurrency control)
    var model = modelBuilder.Build(new System.Data.Entity.Infrastructure.DbProviderInfo("System.Data.SqlClient", "2005"));
    // Compile the model
    var compiledModel = model.Compile();

    // Create the container (DbContext subclass). Ideally all the previous stuff should be cached.
    return new Entities(connection, compiledModel, true);
}

Obviously this needs some reorganization (e.g. cache the compiled model so you don't need to re-build it every time a context is created).

For me this completely solved the problem. Enjoy!

Answer 4

I just had this exact problem but I traced it down to my SQL Server service wasn't running. I had just restarted my computer and usually it starts on it's own but didn't for some reason.

Answer 5

I had this problem when working through the MVC3 tutorial on ASP.NET.

My solution ended up being to use (localhost) instead of a named Data Source. This works fine on my box, for local dev work, but wouldn't help if the database were on a separate server.

Answer 6

Changing to Data Source=localhost worked for me also using MS SQL 2008 R2 Express