This is a simplest approach possible. as_view()
is replaced, so
that it applies the given decorator before returning.
In this approach, decorators are always put on top - that means it's not possible to have functions called in this order:
B.dispatch, login_required, A.dispatch
NOTE: By default this modifies the given class, so be careful when doing this:
TemplateView = view_decorator(login_required)(TemplateView)
Because it will modify the TemplateView class. Instead create a fresh
class first and apply the decorator there. A shortcut for this is
specifying the subclass
argument. But this is also dangerous. Consider:
@view_decorator(login_required, subclass=True)
class MyView(View):
def get_context_data(self):
data = super(MyView, self).get_context_data()
data["foo"] = "bar"
return data
This looks like a normal Python code, but there is a hidden infinite
recursion, because of how super()
works in Python 2.x; By the time
get_context_data()
is invoked, MyView refers to a subclass created in
the decorator. super() looks at the next class in the MRO of MyView,
which is the original MyView class we created, so it contains the
get_context_data()
method. Which is exactly the method that was just
called. BOOM!
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | from functools import wraps
from django.utils.decorators import classonlymethod
def view_decorator(fdec, subclass=False):
"""
Change a function decorator into a view decorator.
https://github.com/lqc/django/tree/cbvdecoration_ticket14512
"""
def decorator(cls):
if not hasattr(cls, "as_view"):
raise TypeError("You should only decorate subclasses of View, not mixins.")
if subclass:
cls = type("%sWithDecorator(%s)" % (cls.__name__, fdec.__name__), (cls,), {})
original = cls.as_view.im_func
@wraps(original)
def as_view(current, **initkwargs):
return fdec(original(current, **initkwargs))
cls.as_view = classonlymethod(as_view)
return cls
return decorator
|
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