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 generating my database as expected.

However, when I run my application outside of a unit test and point it at my connection strings I get the error

ProviderIncompatibleException: The provider did not return a ProviderManifestToken string

I have read the MS documentation on this and it appears this is a SqlVersion token that the EF model generates. The problem is that I am using the code first approach so I have no .edmx file nor do I know where to point my metadata info to because the db hasn't been generated yet.

I know my connection strings as far as db name, username, and pass are correct because changing them to wrong values throws the expected error. Not sure where to begin.

Thanks.

Here is my connection string:

<connectionStrings>   <add     name="SqlConnection"     providerName="System.Data.SqlClient"     connectionString="Data Source=WORKSTATION\SQLEXPRESS;Initial Catalog=CodeFirst;Integrated Security=False;     Persist Security Info=False;User ID=CodeFirst_user;Password=password1;Connect Timeout=120;MultipleActiveResultSets=True;"/> </connectionStrings> 

Answer 1

If you're using EF 6 (just released) you have an alternative.

Dependency Resolution

You can use the new dependency resolution feature to register an implementation of IManifestTokenResolver (described in this preview documentation as IManifestTokenService).

This article gives a bit more information on how to use DbConfiguration. The easiest way to use it is like this:

DbConfigurationType(typeof(EntityFrameworkDbConfiguration))] public class MyContextContext : DbContext { } 

This example avoids any trip to the database when building the metadata for SQL Server connections, and automatically specifies SQL Server 2005 compatability.

using System.Data.Common; using System.Data.Entity; using System.Data.Entity.Infrastructure; using System.Data.Entity.Infrastructure.DependencyResolution; using System.Data.SqlClient;  /// <summary> /// A configuration class for SQL Server that specifies SQL 2005 compatability. /// </summary> internal sealed class EntityFrameworkDbConfiguration : DbConfiguration {     /// <summary>     /// The provider manifest token to use for SQL Server.     /// </summary>     private const string SqlServerManifestToken = @"2005";      /// <summary>     /// Initializes a new instance of the <see cref="EntityFrameworkDbConfiguration"/> class.     /// </summary>     public EntityFrameworkDbConfiguration()     {         this.AddDependencyResolver(new SingletonDependencyResolver<IManifestTokenResolver>(new ManifestTokenService()));     }      /// <inheritdoc />     private sealed class ManifestTokenService : IManifestTokenResolver     {         /// <summary>         /// The default token resolver.         /// </summary>         private static readonly IManifestTokenResolver DefaultManifestTokenResolver = new DefaultManifestTokenResolver();          /// <inheritdoc />         public string ResolveManifestToken(DbConnection connection)         {             if (connection is SqlConnection)             {                 return SqlServerManifestToken;             }              return DefaultManifestTokenResolver.ResolveManifestToken(connection);         }     } } 

Answer 2

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!