how to alter/change the post data in django UpdateView
The QueryDict is mutable after you create its .copy(). See the docs.
Update Example:
class SomeUpdateView(UpdateView): def post(self, request, **kwargs): request.POST = request.POST.copy() request.POST['some_key'] = 'some_value' return super(SomeUpdateView, self).post(request, **kwargs)Here is much broader discussion about the topic.
Furthermore, shouldn't this be done in ModelForm subclass? You're certainly aware you can set custom form as a form_class in UpdateView. Such a logic usually needs unit tests and it's much easier to unit test logic which sits in the form.