Fixed #12749 -- Corrected a problem with validation of inline primary keys....

    def validate(self, value, model_instance):

        if self.rel.parent_link:

            return

        # Don't validate the field if a value wasn't supplied. This is

        # generally the case when saving new inlines in the admin.

        # See #12507.

        if value is None:

            return

        super(ForeignKey, self).validate(value, model_instance)

        if not value:

        if value is None:

            return

        qs = self.rel.to._default_manager.filter(**{self.rel.field_name:value})

        return self.cleaned_data

    def _post_clean(self):

        exclude = self._get_validation_exclusions()

        opts = self._meta

        # Update the model instance with self.cleaned_data.

        self.instance = construct_instance(self, self.instance, opts.fields, opts.exclude)

        exclude = self._get_validation_exclusions()

        # Foreign Keys being used to represent inline relationships

        # are excluded from basic field value validation. This is for two

        # reasons: firstly, the value may not be supplied (#12507; the

        # case of providing new values to the admin); secondly the

        # object being referred to may not yet fully exist (#12749).

        # However, these fields *must* be included in uniqueness checks,

        # so this can't be part of _get_validation_exclusions().

        for f_name, field in self.fields.items():

            if isinstance(field, InlineForeignKeyField):

                exclude.append(f_name)

        # Clean the model instance's fields.

        try:

            self.instance.clean_fields(exclude=exclude)

        unique_check = [field for field in unique_check if field != self.fk.name]

        return super(BaseInlineFormSet, self).get_unique_error_message(unique_check)

def _get_foreign_key(parent_model, model, fk_name=None, can_fail=False):

    """

    Finds and returns the ForeignKey from model to parent if there is one

# only Inline media

admin.site.register(Holder3, inlines=[InnerInline3])

# Models for #12749

class Person(models.Model):

    firstname = models.CharField(max_length=15)

class OutfitItem(models.Model):

    name = models.CharField(max_length=15)

class Fashionista(models.Model):

    person = models.OneToOneField(Person, primary_key=True)

    weaknesses = models.ManyToManyField(OutfitItem, through='ShoppingWeakness', blank=True)

class ShoppingWeakness(models.Model):

    fashionista = models.ForeignKey(Fashionista)

    item = models.ForeignKey(OutfitItem)

class InlineWeakness(admin.TabularInline):

    model = ShoppingWeakness

    extra = 1

admin.site.register(Fashionista, inlines=[InlineWeakness])

__test__ = {'API_TESTS': """

# Regression test for #9362

# local test models

from models import Holder, Inner, InnerInline

from models import Holder2, Inner2, Holder3, Inner3

from models import Person, OutfitItem, Fashionista

class TestInline(TestCase):

    fixtures = ['admin-views-users.xml']

        # The '+' is dropped from the autogenerated form prefix (Author_books+)

        self.assertContains(response, 'id="id_Author_books-TOTAL_FORMS"')

    def test_inline_primary(self):

        person = Person.objects.create(firstname='Imelda')

        item = OutfitItem.objects.create(name='Shoes')

        # Imelda likes shoes, but can't cary her own bags.

        data = {

            'shoppingweakness_set-TOTAL_FORMS': 1,

            'shoppingweakness_set-INITIAL_FORMS': 0,

            'shoppingweakness_set-MAX_NUM_FORMS': 0,

            '_save': u'Save',

            'person': person.id,

            'max_weight': 0,

            'shoppingweakness_set-0-item': item.id,

        }

        response = self.client.post('/test_admin/admin/admin_inlines/fashionista/add/', data)

        self.assertEqual(response.status_code, 302)

        self.assertEqual(len(Fashionista.objects.filter(person__firstname='Imelda')), 1)

class TestInlineMedia(TestCase):

    fixtures = ['admin-views-users.xml']