Django 自动从抽象元类继承 "abstract = true"

Question

我正在使用以下代码。

class CommonFunctions(object):

    def get_absolute_url(self):
        return "/{0}/list/".format(self.__class__.__name__).lower()

    def get_fields(self):
        return [(field, field.value_to_string(self)) for field in   (self.__class__)._meta.fields]

    class Meta:
          abstract = True

类是

class Book(models.Model, CommonFunctions):
        book_name = models.CharField(max_length=30)
        book_area = models.CharField(max_length=30)

现在，如果我使用它，我会得到一个错误，

ForeignKey cannot define a relation with abstract class

但是如果我用

 class Meta:
      abstract = False

然后在 Book 类中它就可以工作了。

如果它们的 documentation 为什么要继承 true说它应该继承false？

Django does make one adjustment to the Meta class of an abstract base class: before installing the Meta attribute, it sets abstract=False. This means that children of abstract base classes don't automatically become abstract classes themselves.

Answer 1

您的CommonFunctions 应该基于models.Model，而不是object。这样，您将获得 Django 文档中所述的行为。

class CommonFunctions(models.Model):

    def get_absolute_url(self):
        return "/{0}/list/".format(self.__class__.__name__).lower()

    def get_fields(self):
        return [(field, field.value_to_string(self)) for field in   (self.__class__)._meta.fields]

    class Meta:
          abstract = True

然后您的 Book 类应该仅基于 CommonFunctions。

class Book(CommonFunctions):
    book_name = models.CharField(max_length=30)
    book_area = models.CharField(max_length=30)