Check extra action func.__name__

[rpkilby]

The extra @action rework is incompatible with some decorator patterns. For example:

def decorate(fn):
    def wrapper(self, request, *args, **kwargs):
        return fn(self, request, *args, **kwargs)
    return wrapper

The issue is that the @action rework looks up functions by their __name__ instead of their actual attribute name on the viewset. Normally, this isn't an issue since the two coincide. In the mean time, the workaround is to use functools.wraps, which will correctly set the __name__.

def decorate(fn):
    @functools.wraps(fn)
    def wrapper(self, request, *args, **kwargs):
        return fn(self, request, *args, **kwargs)
    return wrapper

Fixes #7097

[rpkilby]

So, fixing this isn't really possible given how method mapping works. The method map that's passed to the router maps HTTP methods to viewset method names. However, if an intermediate decorator returns a new function that doesn't use functools.wraps (or otherwise set __name__), then the router is passed a method name that doesn't exist. Take the following:

def decorate(fn):
    # doesn't use @functools.wraps(fn)
    def wrapper(self, request, *args, **kwargs):
        return fn(self, request, *args, **kwargs)
    return wrapper


class MyViewSet(viewsets.ViewSet):

    @action(detail=False)
    @decorate
    def extra(self, request, *args, **kwargs):
        pass

    @action.delete
    @decorate
    def extra_delete(self, request, *args, **kwargs):
        pass

What the router should be passed is {'get': 'extra', 'delete': 'extra_delete'}. However, since @action operates on the function directly, decorate's inner wrapper function is checked instead, creating a map of {'get': 'wrapper', 'delete': 'wrapper'}.

The best we can do is warn the user after the fact. If the attribute name doesn't match the function name, then we can raise an error.

[auvipy]

can we drop python 3.5?

[kevin-brown]

can we drop python 3.5?

Not unless we drop Django 2.2 LTS, which still supports it.

[tomchristie]

There's a conflict that needs resolving, but otherwise leaving this in your hands @rpkilby!
Thanks as ever!!! 😃