Django formsets: make first required?

Question

These formsets are exhibiting exactly the opposite behavior that I want.

My view is set up like this:

def post(request): # TODO: handle vehicle formset     VehicleFormSetFactory = formset_factory(VehicleForm, extra=1)     if request.POST:         vehicles_formset = VehicleFormSetFactory(request.POST)     else:         vehicles_formset = VehicleFormSetFactory() 

And my template looks like this:

    <div id="vehicle_forms">         {{ vehicles_formset.management_form }}         {% for form in vehicles_formset.forms %}             <h4>Vehicle {{forloop.counter}}</h4>             <table>                 {% include "form.html" %}             </table>         {% endfor %}     </div> 

That way it initially generates only 1 form, like I want. But I want that one form to be required!

When I dynamically add blank forms with JavaScript and vehicles_formset.empty_form all those extra forms are required, which I don't want.

From the docs:

The formset is smart enough to ignore extra forms that were not changed.

This is the behavior the first form is exhibiting (not what I want) but not the behavior that the extra forms are exhibiting (what I do want).

Is there some attribute I can can change to at least make one form required?

Answer 1

Found a better solution:

class RequiredFormSet(BaseFormSet):     def __init__(self, *args, **kwargs):         super(RequiredFormSet, self).__init__(*args, **kwargs)         for form in self.forms:             form.empty_permitted = False 

Then create your formset like this:

MyFormSet = formset_factory(MyForm, formset=RequiredFormSet) 

I really don't know why this wasn't an option to begin with... but, whatever. It only took a few hours of my life to figure out.

This will make all the forms required. You could make just the first one required by setting self.forms[0].empty_permitted to False.

Answer 2

New in Django 1.7: you can specify this behaviour with your formset_factory

https://docs.djangoproject.com/en/1.8/topics/forms/formsets/#validate-min

VehicleFormSetFactory = formset_factory(VehicleForm, min_num=1, validate_min=True, extra=1)