Moving Entity framework to another project from MVC causes re-migration
I currently have an asp.net MVC 4 application which contains Entity framework 6 Code First models, DbContext and Migrations. In an attempt to separate this from my web application so I can re-use these database classes in another project I have moved all related Entity Framework classes to their own project.
However now when I run the solution it thinks my model has changed and attempts to run all my migrations once more. The problem appears to be in my use of
SetInitializerpublic static class DatabaseConfig
{
public static void Initialize()
{
System.Data.Entity.Database.SetInitializer(new MigrateDatabaseToLatestVersion<G5DataContext, Configuration>());
// make sure the database is created before SimpleMembership is initialised
using (var db = new G5DataContext())
db.Database.Initialize(true);
}
}
This wasn't a problem until I've tried to move all the Entity Framework classes. Is this not possible, or have I done something fundamentally wrong?
At startup, EF6 queries exiting migrations in your database, as stored in the __MigrationHistory table. Part of this table is a context key, which includes the namespace of the entities.
If you move everything to a new namespace, EF6 doesn't recognize any of the previously run migrations, and tries to rebuild the database.
A quick solution is to run a script to rename the context key in the __MigrationHistory table to your new namespace. From http://jameschambers.com/2014/02/changing-the-namespace-with-entity-framework-6-0-code-first-databases/ :
UPDATE [dbo].[__MigrationHistory]
SET [ContextKey] = 'New_Namespace.Migrations.Configuration'
WHERE [ContextKey] = 'Old_Namespace.Migrations.Configuration'