Question

I’m using EntityFramework 4.3 beta version and its Data Migration facility. I wrote following code for generating a custom Migration and apply it to the DB.

MigrationScaffolder ms=new MigrationScaffolder(configuration);
ScaffoldedMigration scaffoldedMigration= ms.Scaffold("Migration");

DbMigrator dbMigrator = new DbMigrator(configuration);
dbMigrator.Update(scaffoldedMigration.MigrationId);

Scaffolding function worked fine and generated a Migration correctly.

But an exception comes up and says

“The specified target migration ‘201201230637551_Migration’ does not
exist. Ensure that target migration refers to an existing migration
id.”

Does this happen since still this is a beta version? Can someone help me to solve this.

Thank you.

Answer 1

This is not because you were using a beta version. MigrationScaffolder class is only to generate a configuration class. That generated file is not being added to the solution automatically. If we want to pass it into DbMigrator.Update() method, we should add the generated file into the solution first. Then we should make an instance of that class, and pass it into the update() method like this.

{
    DbMigrationsConfiguration myConfiguration=new MyConfiguration();
    DbMigrator dbMigrator = new DbMigrator(configuration);
    dbMigrator.Update(myConfiguration);
}

Here MyConfiguration is the generated class.

Additionally, you do not need to apply migrations into your project this way. Instead you can use:

{
    DbMigrationsConfiguration myConfiguration=new DbMigrationsConfiguration(){
       AutomaticMigrationsEnabled = true;
       AutomaticMigrationDataLossAllowed = true;
    }
    DbMigrator dbMigrator = new DbMigrator(configuration);
    dbMigrator.Update(myConfiguration);
}