问题描述
我正在写一个继承自ListView的视图，并试图将视图限制为登录的用户。
I'm writing a view that inherits from ListView, and am trying to restrict the view to logged-in users.
说，使用URLconf中的login_required进行装饰每个实例都应用装饰器，如果你希望每个视图的实例被装饰，你需要采取不同的方法 - 这种方法是在视图代码中装饰调度方法。
https://docs.djangoproject.com/en/dev/topics/class-based-views/#decorating-in-urlconf says that decorating with login_required in the URLconf "applies the decorator on a per-instance basis. If you want every instance of a view to be decorated, you need to take a different approach" -that approach being to decorate the dispatch method in the view code.
我以为我知道一个类和一个实例之间的区别，但是这个短语不对我来说意味着什么有人可以澄清吗？除了在URLconf中有一个装饰器，而不是在类定义中，两种方法之间有什么区别？
I thought I knew the difference between a class and an instance but this phrase doesn't mean anything to me. Could someone clarify? Apart from having a decorator in the URLconf as opposed to in your class definition, what are the differences between the two approaches?
上面的链接似乎回答了这个问题：由于基于类的视图不是函数，根据您是否使用as_view或创建子类，装饰它们的工作方式不同。
The paragraph above that link seems to answer the question: "Since class-based views aren't functions, decorating them works differently depending on if you're using as_view or creating a subclass."
真的吗我似乎可以用我的ListView子类使用URLconf方法。
Really?? I seem to be able to use the URLconf approach with my subclass of ListView.
推荐答案
想象你有以下类的视图：
Imagine you have the following class based view:
class PostListView(ListView):
model = Post
ProtectedPostListView = login_required(PostListView.as_view())
和您的urls.py：
and your urls.py:
url(r'posts$', ProtectedPostListView)
如果你使用这种方法，那么你将失去子类 ProtectedPostListView 的能力，例如
If you use this approach then you lose the ability to subclass ProtectedPostListView e.g
class MyNewView(ProtectedPostListView):
#IMPOSSIBLE
这是因为 .as_view（）返回一个函数，应用 login_required 装饰器后，您将留下一个函数，因此子类不是
and this is because the .as_view() returns a function and after applying the login_required decorator you are left with a function, so subclassing is not possible.
另一方面，如果你使用第二种方法，即使用方法装饰器子类化是可能的。
eg
On the other hand if you go with the second approach i.e use the method decorator the subclassing is possible.e.g
class PostListView(ListView):
model = Post
@method_decorator(login_required)
def dispatch(self, *args, **kwargs):
return super(PostListView, self).dispatch(*args, **kwargs)
class MyNewView(PostListView):
#LEGAL
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