MigrateDatabaseToLatestVersion and dbo.__MigrationHistory

Question

I am trying to deploy an MVC4 application that is built using EF5 codefist and migrations.

I want the app to update the database when I in the future deploy new versions of the app with new migrations, so in Global.asax I do this:

Database.SetInitializer(new MigrateDatabaseToLatestVersion<GoDealMvc4Context, Configuration>());
using (var ctx = new GoDealMvc4Context()) {
    ctx.Database.Initialize(false);
}

The initial database on the server is deployed by attaching an MDF file copied from my dev machine. This database contains the __MigrationsHistory system table. So this database should not need to execute any migrations, because it is up to date with latest migration.

When I try to start the app on the server, it I get this error:

There is already an object named 'UserProfile' in the database.

[SqlException (0x80131904): There is already an object named 'UserProfile' in the database.]
System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) +388
System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) +688
System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) +4403
System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout) +2755286
System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite) +527
System.Data.SqlClient.SqlCommand.ExecuteNonQuery() +290
System.Data.Entity.Migrations.DbMigrator.ExecuteSql(DbTransaction transaction, MigrationStatement migrationStatement) +247
System.Data.Entity.Migrations.DbMigrator.ExecuteStatements(IEnumerable`1 migrationStatements) +202
System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration) +472
System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId) +175
System.Data.Entity.MigrateDatabaseToLatestVersion`2.InitializeDatabase(TContext context) +150
System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) +66
System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() +225
System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) +208
System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) +235
GoDeal.Mvc4.MvcApplication.Application_Start() +342

So apparently the app thinks it needs to apply a migration even though the __MigrationHistory table is present in the database with this content:

MigrationId                 Model         ProductVersion
201210161046508_initial     0x1F8...      5.0.0.net45

and the app contains a single migration class:

201210161046508_initial.cs:

public partial class initial : DbMigration
{
    public override void Up()
    {
        CreateTable(
            "dbo.UserProfile",
            ....

So my questions are: 1) why do my application think it needs to apply this migration when the contents of the __MigrationsHistory table is as described.

2) is this the recommended way of making an application that automatically applies new migrations wehn restarted on a new version.

Answer 1

There is also another NASTY gotcha here for anyone looking for answers. Check the content of the

[dbo].[__MigrationHistory]   table    column ContextKey

This table Tells how the DB was created (migration mode, Create mode etc...) was created. AND with what Migration Configuration Program. I got hurt with a change of MigrationsConfiguration Class name.

Changing the entry in table worked :-) Or renaming your code back.