Limit Django's inlineformset_factory to only create new objects

Question

I am using django\'s inline formset factory. To use the example in the docs,

author = Author.objects.get(pk=1)
BookFormSet = inlineformset_factory(Author, Book)         


        

Answer 1

inlineformset_factory takes a formset kwarg, which defaults to BaseInlineFormSet. BaseInlineFormSet subclasses BaseModelFormSet, which defines a get_queryset method. If you create a BaseInlineFormSet subclass and override get_queryset to return EmptyQuerySet(), you should get what you're after. In the above example then, it would look like this:

from django.db.models.query import EmptyQuerySet
from django.forms.models import BaseInlineFormSet

class BaseInlineAddOnlyFormSet(BaseInlineFormSet):
    def get_queryset(self):
        return EmptyQuerySet()

author = Author.objects.get(pk=1)
BookFormSet = inlineformset_factory(Author, Book, formset=BaseInlineAddOnlyFormSet)
formset = BookFormSet(request.POST, instance=author)