Django 1.9弃用警告app_label

Question

我刚刚更新到Django v1.8，并在更新项目之前测试了本地设置，并且发出了弃用警告，这是我从未见过的，对我也没有任何意义。我可能只是忽略了某些内容或误解了文档。

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:6: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Difficulty doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Difficulty(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:21: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Zone doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Zone(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:49: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Boss doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Boss(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/raiding/models.py:79: RemovedInDjango19Warning: Model class ankylosguild.apps.raiding.models.Item doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Item(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:14: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Category doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Category(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:36: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Comment doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Comment(ScoreMixin, ProfileMixin, models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:64: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Forum doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Forum(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:88: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.Post doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Post(ScoreMixin, ProfileMixin, models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:119: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.CommentPoint doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class CommentPoint(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/forum/models.py:127: RemovedInDjango19Warning: Model class ankylosguild.apps.forum.models.TopicPoint doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class TopicPoint(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/auctionhouse/models.py:10: RemovedInDjango19Warning: Model class ankylosguild.apps.auctionhouse.models.Auction doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Auction(models.Model):

/Users/neilhickman/Sites/guild/ankylosguild/apps/auctionhouse/models.py:83: RemovedInDjango19Warning: Model class ankylosguild.apps.auctionhouse.models.Bid doesn't declare an explicit app_label and either isn't in an application in INSTALLED_APPS or else was imported before its application was loaded. This will no longer be supported in Django 1.9.
  class Bid(models.Model):

现在，这对我提出了3个问题。

1. 根据文档，Options.app_label除非模型不在应用程序模块之外，否则不是必需的，在我看来，不是这样。其次，无论如何，此行为在1.7中已被弃用，那么为什么它甚至成为问题？
2. 这些应用程序都在INSTALLED_APPS元组中，因此肯定不是吗？
   如果所有内容都在INSTALLED_APPS元组中，为什么在调用应用程序之前不加载它们？
   如果我确实做错了什么，那么做对的正确方法是什么，因为文档并没有真正弄清是什么原因导致了这个问题或如何纠正它。
   
   

Answer 1

如警告中所述，将发生以下两种情况：

• 当你使用不在中的模型时INSTALLED_APPS；
• 或者在加载模型的应用程序之前使用模型。
  由于你确实在INSTALLED_APPS设置中引用了应用程序，因此很可能在应用程序初始化之前就使用了模型。
  

通常，当你有from .models import SomeModels一个apps.py早期信号时（例如post_migrate），就会发生这种情况。建议不要使用AppConfig.get_model（）代替这里的经典方法。检查你的apps.py文件是否有任何模型导入，并使用此api替换它们。

例如代替：

# apps.py

from django.apps import AppConfig
from .models import MyModel

def do_stuff(sender, **kwargs):
    MyModel.objects.get() # etc...

class MyAppConfig(AppConfig):
    name = 'src.my_app_label'

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

做这个 ：

# apps.py

from django.apps import AppConfig

def do_stuff(sender, **kwargs):
    mymodel = sender.get_model('MyModel')
    mymodel.objects.get() # etc...

class MyAppConfig(AppConfig):
    name = 'src.my_app_label'

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

请注意，此强制性是在Bug ＃21719中引入的。