django post_migrate信号问题

Question

由于我在myproject/apps.py文件中有下面的导入行，所以我得到了下面的错误。当我删除这个导入文件，我得到像权限或组无法找到的错误

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

错误消息;

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. 

的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) 

我也曾经在models.py的东西，以确保post_migrate触发 models.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) 

我曾尝试下面的行添加到初始化的.py但它没有帮助 初始化的.py;

default_app_config = 'myproject.apps.MyAppConfig' 

setting.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', 'your_email@example.com'), 
) 

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

发起Django模型前app.py被加载。因此，在执行django\db\models\base.py中的代码时，导入模型会导致错误。

的解决方案是将导入语句移动到方法：

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) 

Answer 2

对于Django的1.10和信号的上方通过其中包含的迁徙运行之后该项目的状态的apps关键字参数（见https://docs.djangoproject.com/en/1.10/ref/signals/#post-migrate）。因此，在使用RunPython创建数据迁移时，可以使用与将apps参数用于函数时相同的方式。

例如MyModel = apps.get_model('my_app', 'MyModel')