Django formsets: make first required?

ghz 1years ago ⋅ 3705 views

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

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.

#django