python - Django mixins.py 和 super() 函数

Question

我尝试了解 mixins.py 中 super() 函数的行为

部分源码： (django\contrib\auth\mixins.py)

class AccessMixin:
    """
    Abstract CBV mixin that gives access mixins the same customizable
    functionality.
    """
    login_url = None
    permission_denied_message = ''
    raise_exception = False
    redirect_field_name = REDIRECT_FIELD_NAME

    def get_login_url(self):
        """
        Override this method to override the login_url attribute.
        """
        login_url = self.login_url or settings.LOGIN_URL
        if not login_url:
            raise ImproperlyConfigured(
                '{0} is missing the login_url attribute. Define {0}.login_url, settings.LOGIN_URL, or override '
                '{0}.get_login_url().'.format(self.__class__.__name__)
            )
        return str(login_url)

    def get_permission_denied_message(self):
        """
        Override this method to override the permission_denied_message attribute.
        """
        return self.permission_denied_message

    def get_redirect_field_name(self):
        """
        Override this method to override the redirect_field_name attribute.
        """
        return self.redirect_field_name

    def handle_no_permission(self):
        if self.raise_exception or self.request.user.is_authenticated:
            raise PermissionDenied(self.get_permission_denied_message())

        path = self.request.build_absolute_uri()
        resolved_login_url = resolve_url(self.get_login_url())
        # If the login url is the same scheme and net location then use the
        # path as the "next" url.
        login_scheme, login_netloc = urlparse(resolved_login_url)[:2]
        current_scheme, current_netloc = urlparse(path)[:2]
        if (
            (not login_scheme or login_scheme == current_scheme) and
            (not login_netloc or login_netloc == current_netloc)
        ):
            path = self.request.get_full_path()
        return redirect_to_login(
            path,
            resolved_login_url,
            self.get_redirect_field_name(),
        )


class LoginRequiredMixin(AccessMixin):
    """Verify that the current user is authenticated."""
    def dispatch(self, request, *args, **kwargs):
        if not request.user.is_authenticated:
            return self.handle_no_permission()
        return super().dispatch(request, *args, **kwargs)

看不懂，最后一排

官方文档说 super() 调用父类。

因此，在这种情况下，它（super()）将在 LoginRequiredMixin 的父类中搜索一个dispatch()方法，即 AccessMixin。但是AccessMixin里面没有dispatch()方法，所以肯定会报这样的错误：

AttributeError: 'super' object has no attribute 'dispatch'

但这一切都有效）而且我无法理解该行的方式和原因，以及该行的作用。谢谢）

标签： pythondjangofunctionmethodsdjango-views