[Answer]-How do I access POST data in overriden form save method?

Post data is assigned to the data attribute of the form:

def save(self, commit=True):
    instance = super(TheForm, self).save(commit=False)
    post_field = self.data['field-name']
    ...

If the form is used in the formset then you should prefix the field name:

self.data[self.prefix + '-field-name']