RunPython migration on second database

Question

Running a database migration with RunPython on a second database fails

python3 manage.py migrate --database=app

The problem is that the apps.get_model method takes the default database which has already the newest migrations.

Does not work:

def copy_cpr_cents_to_euros(apps, schema_editor):
    User = apps.get_model('accounting', 'User')
    User.objects.filter(...);

Works:

def copy_cpr_cents_to_euros(apps, schema_editor):
    User = apps.get_model('accounting', 'User')
    User.objects.using('app').filter(...);

Is there a way to use the given database in the migration, so in this case "app" without making expliclitly declaring it, since it should work for both databases?

So something like:

User.objects.using(database_name).filter(...)

Answer 1

schema_editor.connection.alias

contains the string of the current database with which the migration was started.

So each RunPython-migration must use this alias to manually select the right db.

Example:

def copy_cpr_cents_to_euros(apps, schema_editor):
    User = apps.get_model('accounting', 'User')
    db = schema_editor.connection.alias
    User.objects.using('app').using(db).filter(...)