如何正确地向Django的用户模型添加权限？

Question

我正在尝试向User模型(django.contrib.auth.models)添加自定义权限。

在我的users应用程序的users文件中添加：

from django.db.models.signals import pre_migrate
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth import models as auth_models
from django.contrib.auth.models import Permission
from django.conf import settings
from django.dispatch import receiver


@receiver(pre_migrate, sender=auth_models)
def add_user_permissions(sender, **kwargs):
    content_type = ContentType.objects.get_for_model(settings.AUTH_USER_MODEL)
    Permission.objects.get_or_create(codename='view_user', name=' Can view users', content_type=content_type)
    Permission.objects.get_or_create(codename='change_user_password', name=' Can change user password', content_type=content_type)

settings.py:

INSTALLED_APPS = [
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.forms',
    'django_select2',  # "django-select2" application
    'custom_app',  # "custom_app" application
    'custom_app_2',  # "custom_app_2" application
    'modeltranslation',  # "django-modeltranslation" application
    'users', # "users" application
]

错误：

Traceback (most recent call last):
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/utils/autoreload.py", line 228, in wrapper
    fn(*args, **kwargs)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 117, in inner_run
    autoreload.raise_last_exception()
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/utils/autoreload.py", line 251, in raise_last_exception
    six.reraise(*_exception)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/utils/autoreload.py", line 228, in wrapper
    fn(*args, **kwargs)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/apps/registry.py", line 85, in populate
    app_config = AppConfig.create(entry)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/apps/config.py", line 94, in create
    module = import_module(entry)
  File "/usr/local/Cellar/python/2.7.14/Frameworks/Python.framework/Versions/2.7/lib/python2.7/importlib/__init__.py", line 37, in import_module
    __import__(name)
  File "/Applications/Projects/web/dashboard.kase.kz/users/__init__.py", line 5, in <module>
    from django.contrib.contenttypes.models import ContentType
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/contrib/contenttypes/models.py", line 139, in <module>
    class ContentType(models.Model):
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/db/models/base.py", line 110, in __new__
    app_config = apps.get_containing_app_config(module)
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/apps/registry.py", line 247, in get_containing_app_config
    self.check_apps_ready()
  File "/Users/nurzhan_nogerbek/Virtualenvs/py2714/lib/python2.7/site-packages/django/apps/registry.py", line 125, in check_apps_ready
    raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.

问题：如何修复此错误？

Answer 1

最后，我从文档中找到了解决方案。

1)需要使用下一个命令创建空迁移：

python manage.py makemigrations --empty users

用户-应用程序名称

2)命令创建需要放置下一段代码的0001_initial.py文件：

# -*- coding: utf-8 -*-

from __future__ import unicode_literals
from django.db import migrations

def forwards_func(apps, schema_editor):
    User = apps.get_model('auth', 'User')
    Permission = apps.get_model('auth', 'Permission')
    ContentType = apps.get_model('contenttypes', 'ContentType')
    content_type = ContentType.objects.get_for_model(User)
    db_alias = schema_editor.connection.alias
    Permission.objects.using(db_alias).bulk_create([
        Permission(codename='view_user', name=' Can view users', content_type=content_type),
        Permission(codename='change_user_password', name=' Can change user password', content_type=content_type)
    ])


class Migration(migrations.Migration):

    dependencies = [
    ]

    operations = [
        migrations.RunPython(forwards_func),
    ]

Answer 2

请尝试在init.py文件的顶部添加以下代码：

import django
django.setup()

Answer 3

将init.py中的所有代码复制到一个名为signals.py的新创建文件中，并将__init__.py更改为：

default_app_config = 'user.apps.UserConfig'

signals.py

from django.db.models.signals import pre_migrate
from django.contrib.contenttypes.models import ContentType
from django.contrib.auth.models import AuthConfig
from django.contrib.auth.models import Permission
from django.conf import settings
from django.dispatch import receiver


@receiver(pre_migrate, sender=AuthConfig)
def add_user_permissions(sender, **kwargs):
    content_type = ContentType.objects.get_for_model(settings.AUTH_USER_MODEL)
    Permission.objects.get_or_create(codename='view_user', name=' Can view users', content_type=content_type)
    Permission.objects.get_or_create(codename='change_user_password', name=' Can change user password', content_type=content_type)

然后在user/apps.py中：

from django.apps import AppConfig


class UserConfig(AppConfig):
    name = 'user'
    verbose_name = 'User'

    def ready(self):
        import user.signals

您的错误是足球，因为__init__.py将在models.py中调用用户，但是用户模型将在__init__.py运行后注册，因此您需要在用户模型准备好时调用您的信号。

您希望添加一些与用户相关的perms，因此：

class MyUser(User):

    class Meta:
        permissions = (
            ("view_user", "view_user"),
            ("change_user_password", "change_user_password"),
        )

在settings.py中

AUTH_USER_MODEL = "user.MyUser"