Change a Django form field to a hidden field
an option that worked for me, define the field in the original form as:
forms.CharField(widget = forms.HiddenInput(), required = False)
then when you override it in the new Class it will keep it's place.
If you have a custom template and view you may exclude the field and use {{ modelform.instance.field }}
to get the value.
also you may prefer to use in the view:
form.fields['field_name'].widget = forms.HiddenInput()
but I'm not sure it will protect save method on post.
Hope it helps.
This may also be useful: {{ form.field.as_hidden }}