Entity Framework 4 - Code First and Stored Procedures

I want to execute stored procedure with one parameter that returns table using EF4 "Code First". I am ok with some DTO just for this purpose, it doesn't have to return entities. I have tried to:

a) create edmx file with function import and add it to my ObjectContext like this:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    mod开发者_高级运维elBuilder.RegisterEdmx("Model.edmx");
}

but I got InvalidOperationException saying "Registration of an existing model cannot be used after code first configuration using the fluent API has been started."

b) access underling connection and execute the procedure:

    var connection = this.objectContext.UnderlyingContext.Connection;
    connection.Open();
    DbCommand command = connection.CreateCommand();
    command.CommandType = CommandType.StoredProcedure;
    command.CommandText = "booklog.Recommendations";
    command.Parameters.Add(
        new EntityParameter("userId", DbType.Guid) { Value = this.userId });
    var reader = command.ExecuteReader();
    // etc.

where

public class MyObjectContext : DbContext
{
    public System.Data.Objects.ObjectContext UnderlyingContext
    {
        get { return this.ObjectContext; }
    }

    // ....
 }

but this approach doesn't work as well. It throws InvalidOperationException with message "The container 'booklog' specified for the FunctionImport could not be found in the current workspace."

Ok, b) is correct, but one doesn't have to use UnderlyingContext, just ObjectContext.Database.Connection. Here is the code:

    var connection = this.objectContext.Database.Connection;
    connection.Open();

    DbCommand command = connection.CreateCommand();
    command.CommandType = CommandType.StoredProcedure;
    command.CommandText = "Recommendations";
    command.Parameters.Add(
        new SqlParameter("param", DbType.Guid) { Value = id });

    var reader = command.ExecuteReader();
    while (reader.Read())
    {
        // ...
    }

    connection.Close();