python - "No installed app with label ' 管理员 '"运行 Django 迁移。该应用程序已正确安装

Question

我正在尝试在 Django 1.7 上进行数据迁移期间使用 admin.LogEntry 对象

'django.contrib.admin' 应用程序列在 INSTALLED_APPS 上。

在外壳上，它可以工作:

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

但是在迁移过程中，它失败了:

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

这样失败:

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

使用调试器，我发现“管理员”没有安装:

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']

为什么？？

Answer 1

Django doc说清楚:

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().

代码示例:

# 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),
    ]