EF6 + SQL Server CE + two contexts+ CodeFirst Migrations from code - Detect Pending Changes after Add-Migration

Question

Entity Framework 6.0.2. .Net 4. I am trying to update SQL Server CE 4.0 database from code, so when a new version of the application is released, the database(s) are automatically upgraded.

There are two data contexts in the project and they are targeting two different databases. This is what I am doing to update one of them:

Private Sub UpdateDatabase(connectionString As String)
    Dim config As DbMigrationsConfiguration(Of MainDBContext) = New DbMigrationsConfiguration(Of MainDBContext)()
    config.TargetDatabase = New System.Data.Entity.Infrastructure.DbConnectionInfo(connectionString, "System.Data.SqlServerCe.4.0")
    config.ContextKey = "MyProject.MainDBContext"
    Dim migrator As DbMigrator = New DbMigrator(config)
    migrator.Update()
End Sub

The message from the Update method is that there are pending changes so I have to either run Add-Migration or enable Automatic Migrations. However, Add-Migration has been run and when I do allow automatic migrations, Update tries to create tables which already are in the DB.

Running Update-Database works fine when called like this:

Update-Database -configuration MyProject.MigrationsMainDb.Configuration -Verbose

I checked that the connection string used in the UpdateDatabase function is same as the one in the config file (used by Update-Database). I also tried not setting the ContextKey property, but it made no difference.

Is there anything obvious that I am doing wrong? Why does the migrator thinks there are pending updates but Update-Database is fine...?

Answer 1

I made it working. I realized that instead of creating the "generic" configuration class I should create the configuration class which had been added to the project by Enable-Migrations command. So the code has been changed to the following:

Private Sub UpdateDatabase(connectionString As String)
    Dim config As MigrationsMainDb.Configuration = New MigrationsMainDb.Configuration()
    config.TargetDatabase = New System.Data.Entity.Infrastructure.DbConnectionInfo(connectionString, "System.Data.SqlServerCe.4.0")
    Dim migrator As DbMigrator = New DbMigrator(config)
    migrator.Update()
End Sub

And this change resulted in the configuration object having properties set up correctly. For example the MigrationsDirectory property, which was not set before to what it should be. This was probably the reason of the issue - the migrator not finding migrations (looking for them in wrong directory) and assuming that the whole model has to be applied to the DB.

After making this change, I still had a small glitch with a pending change. In Visual Studio a file looked like modified, with one extra (test) property in the class, but when I tried to remove the extra line, I got a message from VS like "edited on master", or something like that. I closed the file and reopened - the extra property disappeared. I guess it was something with git, checking out branches and VS not refreshing files properly? Not sure really. But once this line was no longer there and the modified code in place, the Update function started working fine.

Update now updates existing databases and successfully creates new ones. Great :)