[Django]-__init__() got multiple values for argument trying to override forms.Form

by

4👍

✅

The order in which you defined the parameters is:

def __init__(self, ubc, *args, **kwargs):

whereas you make a call to the __init__ with:

form = ChangeMemberForm(request.POST, ubc=ubc.id)

So you called it with an unnamed first parameter, whereas the first parameter is ubc. So as a result, the __init__ function received two values for the ubc parameter: request.POST, and ubc.id, and of course that does not make sense.

So you should replace it with:

form = ChangeMemberForm(ubc.id, request.POST)

So here that means that the first parameter (ubc.id) is redirected to the ubc parameter, and the second (request.POST) is the first parameter of the *args, which is a parameter of the super().__init__ call.

👤willeM_ Van Onsem

2👍

The convention in django is to pass the form data as the first positional argument when you initialize a form.

The problem with your ChangeMemberForm is that ubc is declared as the first positional argument. So when you try to ChangeMemberForm(request.POST, ubc=ubc.id) both arguments would be interpreted as ubc, and python throws an exception.

When you subclass Form it’s better to use only named arguments for any extra arguments required by your custom form class. With python 3, simply put ubc between *args and **kwargs in the __init__ method signature. 

class ChangeMemberForm(forms.Form):
    def __init__(self, *args, ubc, **kwargs):
        ...

(If you are using python 3.4 or earlier, you must include a default value for ubc, as mentioned by Willem in a comment)

If you have to support python 2, this syntax is not valid, and you must instead do something like this.

class ChangeMemberForm(forms.Form):
    def __init__(self, *args, **kwargs):
        ubc = kwargs.pop('ubc')
        ...
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