Django 1.7 migration cannot find app

问题:

I'm creating a data migration for app Notification, in here i'm using the reference of model, Manager, from app accounts

Manager = apps.get_model("accounts", "Manager")

It throws error :

    self.code(from_state.render(), schema_editor)
  File "/home/notifications/migrations/0004_auto_20150720_0127.py", line 12, in set_notification_setttings
    Manager = apps.get_model("accounts", "Manager")
  File "/home/local/lib/python2.7/site-packages/django/apps/registry.py", line 202, in get_model
    return self.get_app_config(app_label).get_model(model_name.lower())
  File "/home/local/lib/python2.7/site-packages/django/apps/registry.py", line 150, in get_app_config
    raise LookupError("No installed app with label '%s'." % app_label)
LookupError: No installed app with label 'accounts'

Although from shell i tried something like and it worked

>> from django.apps import apps
>> apps.get_app_config('accounts').get_model('Manager'.lower())
>> accounts.models.Manager

Any light on Why is it failing in case of migration ?

回答1:

Your issue is probably already resolved but somebody else might come across this question.

If the Manager model is not in the same app where you are creating the migration you need to add the dependency for the app accounts in the migration. Example:

class Migration(migrations.Migration):
    dependencies = [
        ('Current_App_Name', 'XYZ_Last_Migration_of_App'),
        ('accounts', '0012_auto_XYZ'),
        ...,
    ]`
    ...