"No installed app with label 'admin'" running Django migration. The app is installed correctly

Question

I am trying to use admin.LogEntry objects during a datamigration on Django 1.7

The 'django.contrib.admin' app is listed on INSTALLED_APPS.

On the shell, it works:

>>> from django.apps import apps
>>> apps.get_model('admin', 'LogEntry')
django.contrib.admin.models.LogEntry

But during the migration, it fails:

def do_it(apps, schema_editor):
    LogEntry = apps.get_model('admin', 'LogEntry')

Fails like this:

django-admin migrate
(...)
LookupError: No installed app with label 'admin'.

Using a debugger, I got that the 'admin' is not installed:

ipdb> apps.get_apps()
[]
ipdb> apps.all_models.keys()
['website', 'google', 'allauth', 'twitter', 'busca', 'conteudo', 'django_mobile', 'django_filters', 'videocenter', 'tinymce', 'oferta', 'programacaotv', 'contenttypes', 'suit', 'haystack', 'destaque', 'filer', 'galeria', 'auth', 'facebook', 'paintstore', 'critica', 'disqus', 'fichas', 'omeletop', 'autocomplete_light', 'modelsv1', 'temas', 'django_extensions', 'adv_cache_tag', 'taggit', 'social', 'personalidade']

WHY??

Answer 1

The Django doc makes it clear:

When writing a RunPython function that uses models from apps other than the one in which the migration is located, the migration’s dependencies attribute should include the latest migration of each app that is involved, otherwise you may get an error similar to: LookupError: No installed app with label 'myappname' when you try to retrieve the model in the RunPython function using apps.get_model().

Code example:

# Imports are omitted for the sake of brevity

def move_m1(apps, schema_editor):
    LogEntry = apps.get('admin.logentry')
    # Other business logic here ...


class Migration(migrations.Migration):

    dependencies = [
        ('app1', '0001_initial'),

        # Below is the manually added dependency, so as to retrieve models
        # of 'django.contrib.admin' app with apps.get_model() in move_m1().
        #
        # Currently this is for Django 1.11. You need to look into
        # 'django/contrib/admin/migrations' directory to find out which is
        # the latest migration for other version of Django.
        ('admin', '0002_logentry_remove_auto_add'),
    ]

    operations = [
        migrations.RunPython(move_m1),
    ]