当我从另一个应用程序导入模型时出现 AttributeError答案

【问题标题】：AttributeError when I import model from another app当我从另一个应用程序导入模型时出现 AttributeError
【发布时间】：2018-07-08 00:16:32
【问题描述】：

我不知道为什么，但我得到了一个错误：AttributeError: module 'downloads.models' has no attribute 'AbstractDownload' 在这个地方：class Download(models_downloads.AbstractDownload):

在下载应用中我已经有AbstractDownload 类

这是我的产品模型

products/models.py
from downloads import models as models_downloads

    class Download(models_downloads.AbstractDownload):
        product = models.ForeignKey('products.Product', related_name='downloads')
        file = FilerFileField(related_name="file_products_download")

这里是下载模型

downloads/models.py
class AbstractDownload(models.Model):
    title = models.CharField(max_length=500)
    subtitle = models.CharField(max_length=1000, blank=True)
    file = FilerFileField(related_name="file_abstract_download")
    order = models.PositiveIntegerField(default=0)

    class Meta:
        abstract = True

        def __str__(self):
            return self.title

追溯：

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/path/venv/lib/python3.5/site-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
    utility.execute()
  File "/path/venv/lib/python3.5/site-packages/django/core/management/__init__.py", line 337, in execute
    django.setup()
  File "/path/venv/lib/python3.5/site-packages/django/__init__.py", line 27, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/path/venv/lib/python3.5/site-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models()
  File "/path/venv/lib/python3.5/site-packages/django/apps/config.py", line 202, in import_models
    self.models_module = import_module(models_module_name)
  File "/path/venv/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 665, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/path/www/downloads/models.py", line 6, in <module>
    from products import models as products_models
  File "/path/www/products/models.py", line 31, in <module>
    class Download(models_downloads.AbstractDownload):
AttributeError: module 'downloads.models' has no attribute 'AbstractDownload'

【问题讨论】：

您是否运行了正确的迁移？
我制作了 python manage.py migrate downloads zero 和 python manage.py migrate products zero 然后更改了代码。但我仍然收到错误@alessioferri20
请尝试 manage.py makemigrations，然后在没有产品零或下载零的情况下进行 manage.py 迁移
我收到了AttributeError: module 'downloads.models' has no attribute 'AbstractDownload'
当你运行上面的命令时？

标签： django django-models import models

【解决方案1】：

你有一个循环导入。您的downloads/models.py 有：

from products import models as products_models

但是你的products/models.py 有

from downloads import models as models_downloads

你还没有展示你如何使用products_models，所以我们不能真正说出如何解决它。以下是一些建议：

如果您使用字符串作为外键，则可能不需要导入，例如models.ForeignKey('downloads.ModelName')
也许您可以移动 AbstractDownload 和 Download 以便它们处于相同的模型中，这样您就不需要导入了
如果您在方法内使用products_models，您可以在方法内移动导入。如果可能，我会避免这种情况。

【讨论】：