Does not work if class based view is decorated.

[sonthonaxrk]

    closure_contents = (c.cell_contents for c in cast(Any, fun).__closure__)
    fun_closure = dict(zip(fun.__code__.co_freevars, closure_contents))
    try:
        class_kwargs = fun_closure['class_kwargs']
    except KeyError:
        # Most likely flask_restful resource, we'll see in a second
        flask_restful_api = fun_closure['self']
        # flask_restful wraps ResourceClass.as_view() result in its own wrapper
        # the as_view() result is available under 'resource' name in this closure
        fun = fun_closure['resource']
        fun_closure = {}
        class_kwargs = {}
        # if the lines above succeeded we're quite sure it's flask_restful resource

The argument fun is the view function. If it's decorated, the value of fun.code.co_freevars will be scoped to the decorator, and it won't include fun_closure['self']