Add an additional form to a formset using POST without Javascript and validation

Question

I want to use a Django formset, but with pure server rendering and without the need of Javascript to add additional forms to it. The user should just click a button on the page and the page should reload with an additional form in the formset. All user input should be preserved! The relevant part in the view is:

if request.POST.get('add_form') == "true":
  cp = request.POST.copy()
  cp['form-TOTAL_FORMS'] = int(cp['form-TOTAL_FORMS']) + 1
  fs = MyFormSet(cp)

The problem is that when MyFormSet(cp) renders a form representation it adds validation errors to it (like "This field is required"). This is ugly and not acceptable. How can I render it without the errors (they should only be present when the whole form was submitted)?

MyFormSet(initial=...) seems not to be an option as it must also work in a UpdateView (the docs are pretty clear that initial is only for extra forms) and also the POST data can't be directly used as initial values.

I am super thankful for any hint as it took me several hours without getting anywhere (and it seems to be such a common feature as the rest of Django is so Javascript agnostic).

medihack · Accepted Answer · 2020-10-18 20:06:55Z

0

It feels like a hack, but this works (after the formset was initialized):

fs._errors = {}
for form in fs:
  form._errors = {}

This removes all errors from the fields when it is rendered to HTML. The background is that when _errors is set to None (the default) the form validates itself when it is rendered. When it is set to an empty dict the form will not validate itself anymore and just "thinks" that there are no errors in it. So no error messages are rendered.

edited Oct 18, 2020 at 20:06

answered Oct 17, 2020 at 21:03

medihack

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