Django使用GenericForeignKey时遭遇AttributeError问题求助

问题场景 #

在VS Code开发Django项目，包含store和tag两个应用，尝试用GenericForeignKey建立标签与store应用中Product模型的关联。运行python manage.py runserver时报错：

AttributeError: module 'django.db.models' has no attribute 'GenericForeignKey'

同时VS Code中from django.contrib.contenttypes.fields import GenericForeignKey这行导入的文本颜色变浅。

原模型代码 #

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey


# Create your models here.
class Tag(models.Model):
    label = models.CharField(max_length=225)

class TaggedField(models.Model):
    #what tag is applied to what object
    tag = models.ForeignKey(Tag, on_delete=models.CASCADE)
    #Type(product,viedo, article)
    #ID
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    object_id = models.PositiveIntegerField()
    content_object = models.GenericForeignKey()

完整报错信息 #

(storefront2) PS C:\Users\kesar\OneDrive\Desktop\storefront2> python manage.py runserver
Watching for file changes with StatReloader
Exception in thread django-main-thread:
Traceback (most recent call last):
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.11_3.11.1520.0_x64__qbz5n2kfra8p0\Lib\threading.py", line 1038, in _bootstrap_inner
    self.run()
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.11_3.11.1520.0_x64__qbz5n2kfra8p0\Lib\threading.py", line 975, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\utils\autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\core\management\commands\runserver.py", line 125, in inner_run
    autoreload.raise_last_exception()
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\utils\autoreload.py", line 87, in raise_last_exception
    raise _exception[1]
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\core\management\__init__.py", line 394, in execute
    autoreload.check_errors(django.setup)()
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\utils\autoreload.py", line 64, in wrapper
    fn(*args, **kwargs)
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\apps\registry.py", line 116, in populate
    app_config.import_models()
  File "C:\Users\kesar\.virtualenvs\storefront2-hockpoA9\Lib\site-packages\django\apps\config.py", line 269, in import_models
    self.models_module = import_module(models_module_name)
                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Program Files\WindowsApps\PythonSoftwareFoundation.Python.3.11_3.11.1520.0_x64__qbz5n2kfra8p0\Lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "C:\Users\kesar\OneDrive\Desktop\storefront2\tags\models.py", line 11, in <module>
    class TaggedField(models.Model):
  File "C:\Users\kesar\OneDrive\Desktop\storefront2\tags\models.py", line 18, in TaggedField
    content_object = models.GenericForeignKey()
                     ^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: module 'django.db.models' has no attribute 'GenericForeignKey'

解决方法 #

你已经正确从django.contrib.contenttypes.fields导入了GenericForeignKey，但在定义content_object字段时错误地使用了models.GenericForeignKey()——GenericForeignKey并不在django.db.models模块中，而是在你已经导入的django.contrib.contenttypes.fields里。

只需把字段定义改为直接使用导入的GenericForeignKey类即可，修复后的完整代码如下：

from django.db import models
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey


# Create your models here.
class Tag(models.Model):
    label = models.CharField(max_length=225)

class TaggedField(models.Model):
    # 标记关联的对象
    tag = models.ForeignKey(Tag, on_delete=models.CASCADE)
    # 关联对象的类型（如Product、Video等）
    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
    # 关联对象的ID
    object_id = models.PositiveIntegerField()
    # 通用外键关联
    content_object = GenericForeignKey()

这样修改后，重新运行python manage.py runserver即可正常启动服务，VS Code中导入语句的颜色也会恢复正常（因为导入的类被实际使用了）。

内容的提问来源于stack exchange，提问作者kesari devaraya