Can Flask-Restful accept case-insensitive argument names?

Question

If I do this with Flask-Restful:

parser = reqparse.RequestParser()
parser.add_argument('group', type=str, help='Please specify a valid group')

then the parser will accept an argument of group=X but not Group=X or GROUP=X.

Is there a way to make it be case-insensitive when taking argument names?

(The reqparse.Argument class has a parameter called case_sensitive but unfortunately that only makes the values case insensitive (by making them lowercase). It doesn't affect the argument name.

Answer 1

Pass a different Argument class to the RequestParser that wraps the args in a case-insensitive MultiDict subclass.

class CaseInsensitiveMultiDict(MultiDict):
    def __init__(self, mapping=None):
        super().__init__(mapping)
        # map lowercase keys to the real keys
        self.lower_key_map = {key.lower(): key for key in self}

    def __contains__(self, key):
        return key.lower() in self.lower_key_map

    def getlist(self, key):
        return super().getlist(self.lower_key_map.get(key.lower()))

    def pop(self, key):
        return super().pop(self.lower_key_map.get(key.lower()))


class CaseInsensitiveArgument(Argument):
    def source(self, request):
        return CaseInsensitiveMultiDict(super().source(request))

parser = RequestParser(argument_class=CaseInsensitiveArgument)

You can still have case-sensitive args by passing an Argument instance to add_argument, rather than keywords.

The MultiDict subclass implements just enough to be case-insensitive for the parser's use case, it's not suitable as a general implementation.