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):
    """
    Allows profile to be added when creating user
    """
    model = Profile


class UserProfileAdmin(admin.ModelAdmin):
    """
    Options for the admin interface
    """
    inlines = [ProfileInline]
    list_display = ['edit_obj', 'name', 'username', 'email', 'is_active',
        'last_login', 'delete_obj']
    list_display_links = ['username']
    list_filter = ['is_active']
    fieldsets = (
        (None, {
            'fields': ('first_name', 'last_name', 'email', 'username',
                'is_active', 'is_superuser')}),
        )
    ordering = ['last_name', 'first_name']
    search_fields = ['first_name', 'last_name']

admin.site.register(User, UserProfileAdmin)

The problem is I need two of the fields in the Profile inline form to be required when adding the user. The inline form doesn't validate unless input is entered. Is there anyway to make the inline required, so that it can't be left blank?

Answer 1

I took Carl's advice and made a much better implementation then the hack-ish one I mentioned in my comment to his answer. Here is my solution:

From my forms.py:

from django.forms.models import BaseInlineFormSet


class RequiredInlineFormSet(BaseInlineFormSet):
    """
    Generates an inline formset that is required
    """

    def _construct_form(self, i, **kwargs):
        """
        Override the method to change the form attribute empty_permitted
        """
        form = super(RequiredInlineFormSet, self)._construct_form(i, **kwargs)
        form.empty_permitted = False
        return form

And the admin.py

class ProfileInline(admin.StackedInline):
    """
    Allows profile to be added when creating user
    """
    model = Profile
    extra = 1
    max_num = 1
    formset = RequiredInlineFormSet


class UserProfileAdmin(admin.ModelAdmin):
    """
    Options for the admin interface
    """
    inlines = [ProfileInline]
    list_display = ['edit_obj', 'name', 'username', 'email', 'is_active',
        'last_login', 'delete_obj']
    list_display_links = ['username']
    list_filter = ['is_active']
    fieldsets = (
        (None, {
            'fields': ('first_name', 'last_name', 'email', 'username',
                'is_active', 'is_superuser')}),
        (('Groups'), {'fields': ('groups', )}),
    )
    ordering = ['last_name', 'first_name']
    search_fields = ['first_name', 'last_name']


admin.site.register(User, UserProfileAdmin)

This does exactly what I want, it makes the Profile inline formset validate. So since there are required fields in the profile form it will validate and fail if the required information isn't entered on the inline form.