python - django post_migrate 信号问题

Question

我收到以下错误，因为我的 myproject/apps.py 文件中有以下导入行。当我删除此导入文件时，出现错误，例如找不到权限或组

from django.contrib.auth.models import Group, Permission

错误信息；

C:\django\myproject>python manage.py migrate myproject
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "C:\Python27\lib\site-packages\django\core\management\__init__.py", line
353, in execute_from_command_line
    utility.execute()
  File "C:\Python27\lib\site-packages\django\core\management\__init__.py", line
327, in execute
    django.setup()
  File "C:\Python27\lib\site-packages\django\__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:\Python27\lib\site-packages\django\apps\registry.py", line 85, in popu
late
    app_config = AppConfig.create(entry)
  File "C:\Python27\lib\site-packages\django\apps\config.py", line 90, in create

    module = import_module(entry)
  File "C:\Python27\lib\importlib\__init__.py", line 37, in import_module
    __import__(name)
  File "C:\django\myproject\myproject\apps.py", line 3, in <module>
    from django.contrib.auth.models import Group, Permission
  File "C:\Python27\lib\site-packages\django\contrib\auth\models.py", line 4, in
 <module>
    from django.contrib.auth.base_user import AbstractBaseUser, BaseUserManager
  File "C:\Python27\lib\site-packages\django\contrib\auth\base_user.py", line 49
, in <module>
    class AbstractBaseUser(models.Model):
  File "C:\Python27\lib\site-packages\django\db\models\base.py", line 94, in __n
ew__
    app_config = apps.get_containing_app_config(module)
  File "C:\Python27\lib\site-packages\django\apps\registry.py", line 239, in get
_containing_app_config
    self.check_apps_ready()
  File "C:\Python27\lib\site-packages\django\apps\registry.py", line 124, in che
ck_apps_ready
    raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.

myproject/apps.py

from django.db.models.signals import post_migrate
from django.apps import AppConfig
from django.contrib.auth.models import Group, Permission


def create_group(name, permissions):
    group = Group.objects.create(name=name)
    [group.permissions.add(permission) for permission in permissions]


def define_company_groups(sender, **kwargs):
    permissions = [
        Permission.objects.get(codename='add_group1_profile'),
        Permission.objects.get(codename='change_group1_profile'),
    ]
    create_group('group1', permissions)


class MyAppConfig(AppConfig):
    name = 'myproject'


    def ready(self):
        post_migrate.connect(define_company_groups, sender=self)

我在 models.py 中还有一些内容，以确保 post_migrate 被触发 模型.py;

from django.db import models

class testmodel(models.Model):

    field1 = models.CharField( max_length=10)
    field2 = models.CharField( max_length=10)
    field3 = models.CharField( max_length=10)

我尝试将以下行添加到 init.py 但没有帮助 init.py;

default_app_config = 'myproject.apps.MyAppConfig'

设置.py

# Build paths inside the project like this: os.path.join(BASE_DIR, ...)
import os
from django.contrib.messages import constants as messages

BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
PROJECT_ROOT = os.path.abspath(os.path.dirname(__file__))

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = 'fhhc#5%c1gn*fdgf4o#a0d*@k)d56^sl*l)aydl5!_sk9_7'

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True
TEMPLATE_DEBUG = DEBUG

ADMINS = (
    # ('Your Name', '<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d2abbda7a08db7bfb3bbbe92b7aab3bfa2beb7fcb1bdbf" rel="noreferrer noopener nofollow">[email protected]</a>'),
)

ALLOWED_HOSTS = []

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}

# MANAGERS = ADMINS
INTERNAL_IPS = ('127.0.0.1',)

# AUTH_USER_MODEL = ''
# AUTHENTICATION_BACKENDS = ('',)
LOGIN_URL = '/login'

SESSION_EXPIRATION_SECONDS = 3600
SESSION_EXPIRE_AT_BROWSER_CLOSE = True

ALLOWED_HOSTS = []
TIME_ZONE = 'GMT'

LANGUAGE_CODE = 'en-us'

LANGUAGES = (
    ('tr', 'Turkish'),
    ('en', 'English'),
    ('de', 'German'),
)

SITE_ID = 1
USE_I18N = True
USE_L10N = True
USE_TZ = True

# Where to look for translations *first*
LOCALE_PATHS = (os.path.join(BASE_DIR, 'locale'),
)

# MEDIA_ROOT = '/var/lib/myproject/media/'
MEDIA_URL = '/media/'

# STATIC_ROOT = '/usr/lib/myproject/static/'
# STATIC_ROOT = os.path.join(BASE_DIR, 'static/')
STATIC_URL = '/static/'
PROJECT_ROOT = os.path.abspath(os.path.dirname(__file__))

# Additional locations of static files
STATICFILES_DIRS = (
    # Put strings here, like "/home/html/static" or "C:/www/django/static".
    # Always use forward slashes, even on Windows.
    # Don't forget to use absolute paths, not relative paths.
    os.path.join(BASE_DIR, 'static'),
)

# List of finder classes that know how to find static files in various
# locations.
STATICFILES_FINDERS = (
    'django.contrib.staticfiles.finders.FileSystemFinder',
    'django.contrib.staticfiles.finders.AppDirectoriesFinder',
)

TEMPLATE_LOADERS = (
    'django.template.loaders.filesystem.Loader',
    'django.template.loaders.app_directories.Loader',
)

# FILE_UPLOAD_HANDLERS = ('',)

MIDDLEWARE_CLASSES = (
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.locale.LocaleMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.security.SecurityMiddleware',
)

ROOT_URLCONF = 'myproject.urls'

WSGI_APPLICATION = 'myproject.wsgi.application'

TEMPLATE_DIRS = (
    # Put strings here, like "/home/html/django_templates" or
    # "C:/www/django/templates".
    # Always use forward slashes, even on Windows.
    # Don't forget to use absolute paths, not relative paths.
    os.path.join(BASE_DIR, 'myproject/templates'),
    os.path.join(BASE_DIR, 'myapp1/templates'),
    os.path.join(BASE_DIR, 'myapp2/templates'),
    os.path.join(BASE_DIR, 'help/templates'),
)

# Application definition
INSTALLED_APPS = (
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.admin',
    'registration',
    'myapp1',
    'myapp2',
    'help',
    'myproject.apps.MyAppConfig',
)

SESSION_SERIALIZER = 'django.contrib.sessions.serializers.JSONSerializer'

LOGGING = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'myproject_format': {
            'format':
                '%(asctime)s %(levelname)s [%(threadName)s]: %(message)s\n'
        },
    },
    'handlers': {
        'django_file': {
            'level': 'ERROR',
            'class': 'logging.FileHandler',
            'filename': os.path.join(BASE_DIR, 'django.log'),
            'formatter': 'myproject_format',
            'encoding': 'utf8',
        },
        'personal_file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': os.path.join(BASE_DIR, 'myapp1.log'),
            'formatter': 'myproject_format',
            'encoding': 'utf8',
        },
        'commercial_file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': os.path.join(BASE_DIR, 'myapp2.log'),
            'formatter': 'myproject_format',
            'encoding': 'utf8',
        },
        'help_file': {
            'level': 'DEBUG',
            'class': 'logging.FileHandler',
            'filename': os.path.join(BASE_DIR, 'help.log'),
            'formatter': 'myproject_format',
            'encoding': 'utf8',
        },
    },
    'loggers': {
        'django': {
            'handlers': ['django_file'],
            'propagate': True,
            'level': 'ERROR',
        },
        'personal': {
            'handlers': ['myapp1_file'],
            'propagate': True,
            'level': 'DEBUG',
        },
        'commercial': {
            'handlers': ['myapp2_file'],
            'propagate': True,
            'level': 'DEBUG',
        },
        'help': {
            'handlers': ['help_file'],
            'propagate': True,
            'level': 'DEBUG',
        },
    }
}


MESSAGE_TAGS = {
    messages.SUCCESS: 'fa fa-check',
    messages.INFO: 'fa fa-info',
    messages.ERROR: 'fa fa-times',
    messages.WARNING: 'fa fa-exclamation',
}

# **********************************************************************************************************************

if DEBUG:
    INTERNAL_IPS = ('127.0.0.1',)
    MIDDLEWARE_CLASSES += (
        'debug_toolbar.middleware.DebugToolbarMiddleware',
    )

    INSTALLED_APPS += (
        'debug_toolbar',
        'django_extensions',
    )

    DEBUG_TOOLBAR_PANELS = [
        'debug_toolbar.panels.versions.VersionsPanel',
        'debug_toolbar.panels.timer.TimerPanel',
        'debug_toolbar.panels.settings.SettingsPanel',
        'debug_toolbar.panels.headers.HeadersPanel',
        'debug_toolbar.panels.request.RequestPanel',
        'debug_toolbar.panels.sql.SQLPanel',
        'debug_toolbar.panels.staticfiles.StaticFilesPanel',
        'debug_toolbar.panels.templates.TemplatesPanel',
        'debug_toolbar.panels.cache.CachePanel',
        'debug_toolbar.panels.signals.SignalsPanel',
        'debug_toolbar.panels.logging.LoggingPanel',
        'debug_toolbar.panels.redirects.RedirectsPanel',
    ]

    DEBUG_TOOLBAR_CONFIG = {
        'INTERCEPT_REDIRECTS': False,
    }

Answer 1

app.py 在 django 模型启动之前加载。因此，在执行 django\db\models\base.py 中的代码时，导入模型会导致错误。

解决方案是将导入语句移至方法中:

def create_group(name, permissions):
    from django.contrib.auth.models import Group

    group = Group.objects.create(name=name)
    [group.permissions.add(permission) for permission in permissions]


def define_company_groups(sender, **kwargs):
    from django.contrib.auth.models import Permission
    permissions = [
        Permission.objects.get(codename='add_group1_profile'),
        Permission.objects.get(codename='change_group1_profile'),
    ]
    create_group('group1', permissions)