Is 'initial' the wrong way to populate a formset?

Using Django Forms & APIs
1

Before I post all the code, this should serve illustrate the problem (or misconception):

all_players = event.participants.all()
print("all_players: ", all_players.count())

only_active_players = all_players.all().filter(status__in=["invited", "confirmed", "waitlisted"]).values()
print("only_active_players: ", only_active_players.count())

formset = ParticipantStatusFormset(initial=only_active_players)
print("forms: ", len(formset))

This reports:

all_players: 3
only_active_players: 2
forms: 3

Do I need to use modelformset_factory instead?

2

Have you verified what’s in those forms?

Based only upon what you’ve posted here, quoting from Formsets | Django documentation | Django

By default, formset_factory() defines one extra form;

3

Yes, all the forms in the formset are fully and correctly populated. It’s just that the ‘initial’ param doesn’t seem to do anything.

4

I’m sorry, I don’t understand.

If:

then what is the issue?

Please be more specific. What are you getting, and what are you expecting to see?

5

I misspoke. The formset is being populated by all 3 of the event.participants, even though the ‘initial’ argument is a list containing only two of them (i.e., a filtered list).

6

Ok, there may be a mismatch between the form and the formset. If you’re using a model form, then you should be using a modelformset, and the queryset for initialization.

If you’re using a regular form (not a model form), then you use initial for initial data.

7

I’m using modelformset_factory: Here’s the form and formset definitions:

class ParticipantStatusForm(forms.ModelForm):
	member_name = forms.CharField(required=True, widget=forms.TextInput())
	status = forms.ChoiceField(required=True, choices=StatusChoices, widget=forms.Select())
	comment = forms.CharField(required=False, widget=forms.Textarea())
	class Meta:
		model = Participant
		fields = ["status","comment","member_name"]

ParticipantStatusFormset = modelformset_factory (
	Participant, 
	form=ParticipantStatusForm,
	fields = ["status","comment","member_name"],
	extra=0, can_delete=False
	)

And the relevant view code:

active_players = event.participants.filter(status__in=["invited", "confirmed", "waitlisted"]).values()
formset = ParticipantStatusFormset(initial=active_players)

If I use queryset instead of initial, the formset gets zero forms:

active_players = event.participants.filter(status__in=["invited", "confirmed", "waitlisted"])
formset = ParticipantStatusFormset(queryset=active_players)

I’m guessing the modelformset_factory (ParticipantStatusFormset) is ignoring the ‘initial’ value and getting all values from the Participant model?

8

Based upon what you’re showing here, it works for me exactly as expected.

This implies either there’s something you’re not showing that is affecting this, or there’s a data issue.

In addition to the link above, on the same page there’s this in the section Providing initial values:

… However, with model formsets, the initial values only apply to extra forms, those that aren’t attached to an existing model instance. …