How do I require an inline in the Django Admin?

Question

I have the following admin setup so that I can add/edit a user and their profile at the same time.

class ProfileInline(admin.StackedInline):
    \"\"\"
             


        

Answer 1

The easiest and most natural way to do that is via fomset clean():

class RequireOneFormSet(forms.models.BaseInlineFormSet):
    def clean(self):
        super().clean()
        if not self.is_valid():
            return
        if not self.forms or not self.forms[0].cleaned_data:
            raise ValidationError('At least one {} required'
                                  .format(self.model._meta.verbose_name))

class ProfileInline(admin.StackedInline):
    model = Profile
    formset =  RequireOneFormSet

(Inspired by this Matthew Flanagan's snippet and Mitar's comment below, tested to work in Django 1.11 and 2.0).