python - 导入错误 : cannot import name <model_class>

Question

我正在使用 forms.ModelChoiceField 从特定模型条目中加载选择:

from order.models import Region

class CheckoutForm(forms.Form):
    area = forms.ModelChoiceField(queryset=Region.objects.all(),label=("Area"))

我面临的问题是，从应用程序导入类名时。我收到错误:

ImportError: cannot import name Region

请注意，在 shell 中独立测试时，from order.models import Region 正在运行。

知道是什么原因造成的吗？

Traceback (most recent call last):
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 92, in inner_run
    self.validate(display_num_errors=True)
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/core/management/base.py", line 280, in validate
    num_errors = get_validation_errors(s, app)
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/core/management/validation.py", line 35, in get_validation_errors
    for (app_name, error) in get_app_errors().items():
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/db/models/loading.py", line 166, in get_app_errors
    self._populate()
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/db/models/loading.py", line 75, in _populate
    self.load_app(app_name)
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/db/models/loading.py", line 96, in load_app
    models = import_module('.models', app_name)
  File "/home/salma/venv/local/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/home/salma/Projects/Morabiz/Saludable/saludable_django/landing/models.py", line 2, in <module>
    from order.models import Dish
  File "/home/salma/Projects/Morabiz/Saludable/saludable_django/order/models.py", line 4, in <module>
    from order.forms import RegistrationFormNoUserName
  File "/home/salma/Projects/Morabiz/Saludable/saludable_django/order/forms.py", line 7, in <module>
    from order.models import Region
ImportError: cannot import name Region

Answer 1

正如我在评论中提到的，您的表单和模型文件之间存在循环依赖关系。您要么需要重构以消除循环性，要么如果您真的做不到，则必须将其中一个导入移动到使用它的函数中。