Modify data incoming to django form before cleaning

Question

I need do modify data incoming to Form before cleaning. I made it work, but It looks awful:

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


        

Answer 1

Make data the first argument of the __init__ method, the same as the super class Form. That way you don't have to dig about in args or kwargs.

def __init__(self, data=None, *args, **kwargs):
    if data is not None:
        data = data.copy() # make it mutable
        data['content'] = ' '.join(data['content'].strip().split())
    super(TagForm, self).__init__(data, *args, **kwargs)

Answer 2

You can compress the if / elif / else onto one line easily enough:

def __init__(self, *args, **kwargs):
    data = args[0] if args else kwargs.get('data', None)
    if data:
        data['content'] = ' '.join(data['content'].strip().split())
    super(TagForm, self).__init__(*args, **kwargs)

if args works as well as if len(args) > 0 because length == 0 items are False and length > 0 items are True.

if data works as well as if data is not None because you're assuming that data has at least one key if it's not None anyway, and if it has a key it's True.

Answer 3

As stated in the documentation for form and field validation you can not do it on form level, so the __init__ method seems the most legit way. You can of course also modify the data before passing it to the form (for example in your view or wherever you process the form).

Answer 4

I found another solution:

def clean(self, *args, **kwargs):
    data = dict(self.data)
    if 'content' in data:
        content = data['content']
        if isinstance(content, list):
            content = content[0] # QueryDict wraps even single values to list
        data['content'] = ' '.join(content.strip().split())
    self.data = data # I do this trick becouse request.POST is immutable
    return super(MyForm, self).clean(*args, **kwargs)

UPD: error fix: super(self.__class__, self) may cause infinite recursion if I use form inheritance :).

UPD: seems still have troubles, and not work correctly.