Django模型“没有显式声明app_label”

我真是一筹莫及。经过十几个小时的故障排除，可能更多，我以为我终于可以做生意了，但接着我发现:

Model class django.contrib.contenttypes.models.ContentType doesn't declare an explicit app_label

网上关于这方面的信息太少了，没有解决方案可以解决我的问题。任何建议都将不胜感激。

我使用的是Python 3.4和Django 1.10。

从我的settings.py:

INSTALLED_APPS = [
    'DeleteNote.apps.DeletenoteConfig',
    'LibrarySync.apps.LibrarysyncConfig',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
]

我的app .py文件是这样的:

from django.apps import AppConfig


class DeletenoteConfig(AppConfig):
    name = 'DeleteNote'

and

from django.apps import AppConfig


class LibrarysyncConfig(AppConfig):
    name = 'LibrarySync'

当前回答

这里没有一个答案解决了我的问题，把我们都带到这里的错误消息对我来说是一个转移注意力的错误消息——但我确实找到了一个解决方案。

对我来说，这个问题的真正原因是:

Django tries to register apps Some exception occurs during app registration (root cause) Something in exception handling tooling pulls in a model somewhere That model lives in an app that hasn't been registered (because, remember, app registration was broken by the root cause exception above) Finally, as its last act before dying Django spits out the (red herring) complaint that brought us all here - i.e. SomeModel doesn't declare an explicit app_label and isn't in an application in INSTALLED_APPS.

而不是关心这个错误(即把我们带到这里的错误)，我需要向上滚动并阅读第一条错误消息。

这可能看起来像别的东西，它可以是任何打破应用注册。对我来说，根本原因是:

Traceback (most recent call last):
[...SNIP...]                                                                                                                                                                                      
  File "/Users/user/.pyenv/versions/appName_py3/lib/python3.7/site-packages/django/__init__.py", line 24, in setup                   
    apps.populate(settings.INSTALLED_APPS)                                                                                         
  File "/Users/user/.pyenv/versions/appName_py3/lib/python3.7/site-packages/django/apps/registry.py", line 114, in populate 
    app_config.import_models()                                                                                                       
[... SNIP ...]                                                                                                    
  File "/Users/user/app_name/api/models/models.py", line 1122, in <module>              
    class SomeObject(models.Model):                                                                                     
  File "/Users/user/dev_alt/app_name/api/models/models.py", line 1134, in SomeObject
    some_property = models.ForeignKey(SomeOtherObject, null=True, blank=True)                         
TypeError: __init__() missing 1 required positional argument: 'on_delete'   

[...SNIP...]
During handling of the above exception, another exception occurred:

<RED HERRING STACK TRACE THAT BROUGHT US ALL HERE>

同样，“根本原因”问题对你来说可能不同——但对我来说是不同的:我正在从1.11升级一个遗留的Django应用程序。X ~ 3.2.x。在此过程中，Django做了一个破坏向后兼容性的改变，要求模型上所有的ForeignKey和OneToOne属性都有一个on_delete参数。

我为应用程序中的200多个违规情况添加了这个参数，我的根本原因问题和没有声明显式app_label问题都得到了解决。

2022-01-18 01:21:16

其他回答

我只是遇到了这个问题，并找出了哪里出了问题。由于之前的回答没有描述这个问题发生在我身上，我想我可以把它发布给其他人:

the issue came from using python migrate.py startapp myApp from my project root folder, then move myApp to a child folder with mv myApp myFolderWithApps/. I wrote myApp.models and ran python migrate.py makemigrations. All went well. then I did the same with another app that was importing models from myApp. Kaboom! I ran into this error, while performing makemigrations. That was because I had to use myFolderWithApps.myApp to reference my app, but I had forgotten to update MyApp/apps.py. So I corrected myApp/apps.py, settings/INSTALLED_APPS and my import path in my second app. but then the error kept happening: the reason was that I had migrations trying to import the models from myApp with the wrong path. I tried to correct the migration file, but I went at the point where it was easier to reset the DB and delete the migrations to start from scratch.

长话短说: -这个问题最初是来自myApp的apps.py中的应用程序名称错误，在设置和我的第二个应用程序的导入路径。 -但仅仅纠正这三个地方的路径是不够的，因为导入时引用了错误的应用程序名称。因此，同样的错误在迁移过程中不断发生(除了这次是从迁移中)。

所以…检查您的迁移，祝您好运!

2018-03-15 22:58:46

您是否遗漏了将应用程序名称放入设置文件中? myAppNameConfig是由.manage.py createapp myAppName命令在apps.py中生成的默认类。其中myAppName是应用程序的名称。

settings.py

INSTALLED_APPS = [
'myAppName.apps.myAppNameConfig',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
]

这样，设置文件就会找到您想要调用应用程序的内容。您可以通过在apps.py文件中添加以下代码来更改它的外观

我的应用名称/应用程序.py

class myAppNameConfig(AppConfig):
    name = 'myAppName'
    verbose_name = 'A Much Better Name'

2016-10-23 18:56:07

我今天也收到了这个错误。消息引用到我的应用程序在INSTALLED_APPS的一些特定的应用程序。但事实上，它与这个特定的应用程序无关。我使用了一个新的虚拟环境，忘记安装一些库，我在这个项目中使用。在我安装了额外的库后，它工作了。

2019-04-26 13:15:31

还要检查您的迁移是否正常工作

Python3 manage.py makemigrations
Python3 manage.py migrate

2020-12-28 06:42:17