from django.db import models

try:
    sorted
except NameError:
    from django.utils.itercompat import sorted

class Author(models.Model):
    name = models.CharField(max_length=100)

    class Meta:
        ordering = ('name',)

    def __unicode__(self):
        return self.name

class BetterAuthor(Author):
    write_speed = models.IntegerField()

class Book(models.Model):
    author = models.ForeignKey(Author)
    title = models.CharField(max_length=100)

    def __unicode__(self):
        return self.title

class AuthorMeeting(models.Model):
    name = models.CharField(max_length=100)
    authors = models.ManyToManyField(Author)
    created = models.DateField(editable=False)

    def __unicode__(self):
        return self.name

class CustomPrimaryKey(models.Model):
    my_pk = models.CharField(max_length=10, primary_key=True)
    some_field = models.CharField(max_length=100)


# models for inheritance tests.

class Place(models.Model):
    name = models.CharField(max_length=50)
    city = models.CharField(max_length=50)
    
    def __unicode__(self):
        return self.name

class Owner(models.Model):
    auto_id = models.AutoField(primary_key=True)
    name = models.CharField(max_length=100)
    place = models.ForeignKey(Place)
    
    def __unicode__(self):
        return "%s at %s" % (self.name, self.place)

class Location(models.Model):
    place = models.ForeignKey(Place, unique=True)
    # this is purely for testing the data doesn't matter here :)
    lat = models.CharField(max_length=100)
    lon = models.CharField(max_length=100)

class OwnerProfile(models.Model):
    owner = models.OneToOneField(Owner, primary_key=True)
    age = models.PositiveIntegerField()
    
    def __unicode__(self):
        return "%s is %d" % (self.owner.name, self.age)

class Restaurant(Place):
    serves_pizza = models.BooleanField()
    
    def __unicode__(self):
        return self.name

class MexicanRestaurant(Restaurant):
    serves_tacos = models.BooleanField()


__test__ = {'API_TESTS': """

>>> from datetime import date

>>> from django.forms.models import modelformset_factory

>>> qs = Author.objects.all()
>>> AuthorFormSet = modelformset_factory(Author, extra=3)

>>> formset = AuthorFormSet(queryset=qs)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-name">Name:</label> <input id="id_form-0-name" type="text" name="form-0-name" maxlength="100" /><input type="hidden" name="form-0-id" id="id_form-0-id" /></p>
<p><label for="id_form-1-name">Name:</label> <input id="id_form-1-name" type="text" name="form-1-name" maxlength="100" /><input type="hidden" name="form-1-id" id="id_form-1-id" /></p>
<p><label for="id_form-2-name">Name:</label> <input id="id_form-2-name" type="text" name="form-2-name" maxlength="100" /><input type="hidden" name="form-2-id" id="id_form-2-id" /></p>

>>> data = {
...     'form-TOTAL_FORMS': '3', # the number of forms rendered
...     'form-INITIAL_FORMS': '0', # the number of forms with initial data
...     'form-0-name': 'Charles Baudelaire',
...     'form-1-name': 'Arthur Rimbaud',
...     'form-2-name': '',
... }

>>> formset = AuthorFormSet(data=data, queryset=qs)
>>> formset.is_valid()
True

>>> formset.save()
[<Author: Charles Baudelaire>, <Author: Arthur Rimbaud>]

>>> for author in Author.objects.order_by('name'):
...     print author.name
Arthur Rimbaud
Charles Baudelaire


Gah! We forgot Paul Verlaine. Let's create a formset to edit the existing
authors with an extra form to add him. We *could* pass in a queryset to
restrict the Author objects we edit, but in this case we'll use it to display
them in alphabetical order by name.

>>> qs = Author.objects.order_by('name')
>>> AuthorFormSet = modelformset_factory(Author, extra=1, can_delete=False)

>>> formset = AuthorFormSet(queryset=qs)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-name">Name:</label> <input id="id_form-0-name" type="text" name="form-0-name" value="Arthur Rimbaud" maxlength="100" /><input type="hidden" name="form-0-id" value="2" id="id_form-0-id" /></p>
<p><label for="id_form-1-name">Name:</label> <input id="id_form-1-name" type="text" name="form-1-name" value="Charles Baudelaire" maxlength="100" /><input type="hidden" name="form-1-id" value="1" id="id_form-1-id" /></p>
<p><label for="id_form-2-name">Name:</label> <input id="id_form-2-name" type="text" name="form-2-name" maxlength="100" /><input type="hidden" name="form-2-id" id="id_form-2-id" /></p>


>>> data = {
...     'form-TOTAL_FORMS': '3', # the number of forms rendered
...     'form-INITIAL_FORMS': '2', # the number of forms with initial data
...     'form-0-id': '2',
...     'form-0-name': 'Arthur Rimbaud',
...     'form-1-id': '1',
...     'form-1-name': 'Charles Baudelaire',
...     'form-2-name': 'Paul Verlaine',
... }

>>> formset = AuthorFormSet(data=data, queryset=qs)
>>> formset.is_valid()
True

# Only changed or new objects are returned from formset.save()
>>> formset.save()
[<Author: Paul Verlaine>]

>>> for author in Author.objects.order_by('name'):
...     print author.name
Arthur Rimbaud
Charles Baudelaire
Paul Verlaine


This probably shouldn't happen, but it will. If an add form was marked for
deltetion, make sure we don't save that form.

>>> qs = Author.objects.order_by('name')
>>> AuthorFormSet = modelformset_factory(Author, extra=1, can_delete=True)

>>> formset = AuthorFormSet(queryset=qs)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-name">Name:</label> <input id="id_form-0-name" type="text" name="form-0-name" value="Arthur Rimbaud" maxlength="100" /></p>
<p><label for="id_form-0-DELETE">Delete:</label> <input type="checkbox" name="form-0-DELETE" id="id_form-0-DELETE" /><input type="hidden" name="form-0-id" value="2" id="id_form-0-id" /></p>
<p><label for="id_form-1-name">Name:</label> <input id="id_form-1-name" type="text" name="form-1-name" value="Charles Baudelaire" maxlength="100" /></p>
<p><label for="id_form-1-DELETE">Delete:</label> <input type="checkbox" name="form-1-DELETE" id="id_form-1-DELETE" /><input type="hidden" name="form-1-id" value="1" id="id_form-1-id" /></p>
<p><label for="id_form-2-name">Name:</label> <input id="id_form-2-name" type="text" name="form-2-name" value="Paul Verlaine" maxlength="100" /></p>
<p><label for="id_form-2-DELETE">Delete:</label> <input type="checkbox" name="form-2-DELETE" id="id_form-2-DELETE" /><input type="hidden" name="form-2-id" value="3" id="id_form-2-id" /></p>
<p><label for="id_form-3-name">Name:</label> <input id="id_form-3-name" type="text" name="form-3-name" maxlength="100" /></p>
<p><label for="id_form-3-DELETE">Delete:</label> <input type="checkbox" name="form-3-DELETE" id="id_form-3-DELETE" /><input type="hidden" name="form-3-id" id="id_form-3-id" /></p>

>>> data = {
...     'form-TOTAL_FORMS': '4', # the number of forms rendered
...     'form-INITIAL_FORMS': '3', # the number of forms with initial data
...     'form-0-id': '2',
...     'form-0-name': 'Arthur Rimbaud',
...     'form-1-id': '1',
...     'form-1-name': 'Charles Baudelaire',
...     'form-2-id': '3',
...     'form-2-name': 'Paul Verlaine',
...     'form-3-name': 'Walt Whitman',
...     'form-3-DELETE': 'on',
... }

>>> formset = AuthorFormSet(data=data, queryset=qs)
>>> formset.is_valid()
True

# No objects were changed or saved so nothing will come back.
>>> formset.save()
[]

>>> for author in Author.objects.order_by('name'):
...     print author.name
Arthur Rimbaud
Charles Baudelaire
Paul Verlaine

Let's edit a record to ensure save only returns that one record.

>>> data = {
...     'form-TOTAL_FORMS': '4', # the number of forms rendered
...     'form-INITIAL_FORMS': '3', # the number of forms with initial data
...     'form-0-id': '2',
...     'form-0-name': 'Walt Whitman',
...     'form-1-id': '1',
...     'form-1-name': 'Charles Baudelaire',
...     'form-2-id': '3',
...     'form-2-name': 'Paul Verlaine',
...     'form-3-name': '',
...     'form-3-DELETE': '',
... }

>>> formset = AuthorFormSet(data=data, queryset=qs)
>>> formset.is_valid()
True

# One record has changed.
>>> formset.save()
[<Author: Walt Whitman>]

Test the behavior of commit=False and save_m2m

>>> meeting = AuthorMeeting.objects.create(created=date.today())
>>> meeting.authors = Author.objects.all()

# create an Author instance to add to the meeting.
>>> new_author = Author.objects.create(name=u'John Steinbeck')

>>> AuthorMeetingFormSet = modelformset_factory(AuthorMeeting, extra=1, can_delete=True)
>>> data = {
...     'form-TOTAL_FORMS': '2', # the number of forms rendered
...     'form-INITIAL_FORMS': '1', # the number of forms with initial data
...     'form-0-id': '1',
...     'form-0-name': '2nd Tuesday of the Week Meeting',
...     'form-0-authors': [2, 1, 3, 4],
...     'form-1-name': '',
...     'form-1-authors': '',
...     'form-1-DELETE': '',
... }
>>> formset = AuthorMeetingFormSet(data=data, queryset=AuthorMeeting.objects.all())
>>> formset.is_valid()
True
>>> instances = formset.save(commit=False)
>>> for instance in instances:
...     instance.created = date.today()
...     instance.save()
>>> formset.save_m2m()
>>> instances[0].authors.all()
[<Author: Charles Baudelaire>, <Author: John Steinbeck>, <Author: Paul Verlaine>, <Author: Walt Whitman>]

# delete the author we created to allow later tests to continue working.
>>> new_author.delete()

Test the behavior of max_num with model formsets. It should properly limit
the queryset to reduce the amount of objects being pulled in when not being
used.

>>> qs = Author.objects.order_by('name')

>>> AuthorFormSet = modelformset_factory(Author, max_num=2)
>>> formset = AuthorFormSet(queryset=qs)
>>> [sorted(x.items()) for x in formset.initial]
[[('id', 1), ('name', u'Charles Baudelaire')], [('id', 3), ('name', u'Paul Verlaine')]]

>>> AuthorFormSet = modelformset_factory(Author, max_num=3)
>>> formset = AuthorFormSet(queryset=qs)
>>> [sorted(x.items()) for x in formset.initial]
[[('id', 1), ('name', u'Charles Baudelaire')], [('id', 3), ('name', u'Paul Verlaine')], [('id', 2), ('name', u'Walt Whitman')]]

# Model inheritance in model formsets ########################################

>>> BetterAuthorFormSet = modelformset_factory(BetterAuthor)
>>> formset = BetterAuthorFormSet()
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-name">Name:</label> <input id="id_form-0-name" type="text" name="form-0-name" maxlength="100" /></p>
<p><label for="id_form-0-write_speed">Write speed:</label> <input type="text" name="form-0-write_speed" id="id_form-0-write_speed" /><input type="hidden" name="form-0-author_ptr" id="id_form-0-author_ptr" /></p>

>>> data = {
...     'form-TOTAL_FORMS': '1', # the number of forms rendered
...     'form-INITIAL_FORMS': '0', # the number of forms with initial data
...     'form-0-author_ptr': '',
...     'form-0-name': 'Ernest Hemingway',
...     'form-0-write_speed': '10',
... }

>>> formset = BetterAuthorFormSet(data)
>>> formset.is_valid()
True
>>> formset.save()
[<BetterAuthor: Ernest Hemingway>]
>>> hemingway_id = BetterAuthor.objects.get(name="Ernest Hemingway").pk

>>> formset = BetterAuthorFormSet()
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-name">Name:</label> <input id="id_form-0-name" type="text" name="form-0-name" value="Ernest Hemingway" maxlength="100" /></p>
<p><label for="id_form-0-write_speed">Write speed:</label> <input type="text" name="form-0-write_speed" value="10" id="id_form-0-write_speed" /><input type="hidden" name="form-0-author_ptr" value="..." id="id_form-0-author_ptr" /></p>
<p><label for="id_form-1-name">Name:</label> <input id="id_form-1-name" type="text" name="form-1-name" maxlength="100" /></p>
<p><label for="id_form-1-write_speed">Write speed:</label> <input type="text" name="form-1-write_speed" id="id_form-1-write_speed" /><input type="hidden" name="form-1-author_ptr" id="id_form-1-author_ptr" /></p>

>>> data = {
...     'form-TOTAL_FORMS': '2', # the number of forms rendered
...     'form-INITIAL_FORMS': '1', # the number of forms with initial data
...     'form-0-author_ptr': hemingway_id,
...     'form-0-name': 'Ernest Hemingway',
...     'form-0-write_speed': '10',
...     'form-1-author_ptr': '',
...     'form-1-name': '',
...     'form-1-write_speed': '',
... }

>>> formset = BetterAuthorFormSet(data)
>>> formset.is_valid()
True
>>> formset.save()
[]

# Inline Formsets ############################################################

We can also create a formset that is tied to a parent model. This is how the
admin system's edit inline functionality works.

>>> from django.forms.models import inlineformset_factory

>>> AuthorBooksFormSet = inlineformset_factory(Author, Book, can_delete=False, extra=3)
>>> author = Author.objects.get(name='Charles Baudelaire')

>>> formset = AuthorBooksFormSet(instance=author)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_book_set-0-title">Title:</label> <input id="id_book_set-0-title" type="text" name="book_set-0-title" maxlength="100" /><input type="hidden" name="book_set-0-id" id="id_book_set-0-id" /></p>
<p><label for="id_book_set-1-title">Title:</label> <input id="id_book_set-1-title" type="text" name="book_set-1-title" maxlength="100" /><input type="hidden" name="book_set-1-id" id="id_book_set-1-id" /></p>
<p><label for="id_book_set-2-title">Title:</label> <input id="id_book_set-2-title" type="text" name="book_set-2-title" maxlength="100" /><input type="hidden" name="book_set-2-id" id="id_book_set-2-id" /></p>

>>> data = {
...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
...     'book_set-INITIAL_FORMS': '0', # the number of forms with initial data
...     'book_set-0-title': 'Les Fleurs du Mal',
...     'book_set-1-title': '',
...     'book_set-2-title': '',
... }

>>> formset = AuthorBooksFormSet(data, instance=author)
>>> formset.is_valid()
True

>>> formset.save()
[<Book: Les Fleurs du Mal>]

>>> for book in author.book_set.all():
...     print book.title
Les Fleurs du Mal


Now that we've added a book to Charles Baudelaire, let's try adding another
one. This time though, an edit form will be available for every existing
book.

>>> AuthorBooksFormSet = inlineformset_factory(Author, Book, can_delete=False, extra=2)
>>> author = Author.objects.get(name='Charles Baudelaire')

>>> formset = AuthorBooksFormSet(instance=author)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_book_set-0-title">Title:</label> <input id="id_book_set-0-title" type="text" name="book_set-0-title" value="Les Fleurs du Mal" maxlength="100" /><input type="hidden" name="book_set-0-id" value="1" id="id_book_set-0-id" /></p>
<p><label for="id_book_set-1-title">Title:</label> <input id="id_book_set-1-title" type="text" name="book_set-1-title" maxlength="100" /><input type="hidden" name="book_set-1-id" id="id_book_set-1-id" /></p>
<p><label for="id_book_set-2-title">Title:</label> <input id="id_book_set-2-title" type="text" name="book_set-2-title" maxlength="100" /><input type="hidden" name="book_set-2-id" id="id_book_set-2-id" /></p>

>>> data = {
...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
...     'book_set-INITIAL_FORMS': '1', # the number of forms with initial data
...     'book_set-0-id': '1',
...     'book_set-0-title': 'Les Fleurs du Mal',
...     'book_set-1-title': 'Le Spleen de Paris',
...     'book_set-2-title': '',
... }

>>> formset = AuthorBooksFormSet(data, instance=author)
>>> formset.is_valid()
True

>>> formset.save()
[<Book: Le Spleen de Paris>]

As you can see, 'Le Spleen de Paris' is now a book belonging to Charles Baudelaire.

>>> for book in author.book_set.order_by('id'):
...     print book.title
Les Fleurs du Mal
Le Spleen de Paris

The save_as_new parameter lets you re-associate the data to a new instance.
This is used in the admin for save_as functionality.

>>> data = {
...     'book_set-TOTAL_FORMS': '3', # the number of forms rendered
...     'book_set-INITIAL_FORMS': '2', # the number of forms with initial data
...     'book_set-0-id': '1',
...     'book_set-0-title': 'Les Fleurs du Mal',
...     'book_set-1-id': '2',
...     'book_set-1-title': 'Le Spleen de Paris',
...     'book_set-2-title': '',
... }

>>> formset = AuthorBooksFormSet(data, instance=Author(), save_as_new=True)
>>> formset.is_valid()
True

>>> new_author = Author.objects.create(name='Charles Baudelaire')
>>> formset.instance = new_author
>>> [book for book in formset.save() if book.author.pk == new_author.pk]
[<Book: Les Fleurs du Mal>, <Book: Le Spleen de Paris>]

Test using a custom prefix on an inline formset.

>>> formset = AuthorBooksFormSet(prefix="test")
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_test-0-title">Title:</label> <input id="id_test-0-title" type="text" name="test-0-title" maxlength="100" /><input type="hidden" name="test-0-id" id="id_test-0-id" /></p>
<p><label for="id_test-1-title">Title:</label> <input id="id_test-1-title" type="text" name="test-1-title" maxlength="100" /><input type="hidden" name="test-1-id" id="id_test-1-id" /></p>

# Test a custom primary key ###################################################

We need to ensure that it is displayed

>>> CustomPrimaryKeyFormSet = modelformset_factory(CustomPrimaryKey)
>>> formset = CustomPrimaryKeyFormSet()
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-my_pk">My pk:</label> <input id="id_form-0-my_pk" type="text" name="form-0-my_pk" maxlength="10" /></p>
<p><label for="id_form-0-some_field">Some field:</label> <input id="id_form-0-some_field" type="text" name="form-0-some_field" maxlength="100" /></p>

# Custom primary keys with ForeignKey, OneToOneField and AutoField ############

>>> place = Place(name=u'Giordanos', city=u'Chicago')
>>> place.save()

>>> FormSet = inlineformset_factory(Place, Owner, extra=2, can_delete=False)
>>> formset = FormSet(instance=place)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_owner_set-0-name">Name:</label> <input id="id_owner_set-0-name" type="text" name="owner_set-0-name" maxlength="100" /><input type="hidden" name="owner_set-0-auto_id" id="id_owner_set-0-auto_id" /></p>
<p><label for="id_owner_set-1-name">Name:</label> <input id="id_owner_set-1-name" type="text" name="owner_set-1-name" maxlength="100" /><input type="hidden" name="owner_set-1-auto_id" id="id_owner_set-1-auto_id" /></p>

>>> data = {
...     'owner_set-TOTAL_FORMS': '2',
...     'owner_set-INITIAL_FORMS': '0',
...     'owner_set-0-auto_id': '',
...     'owner_set-0-name': u'Joe Perry',
...     'owner_set-1-auto_id': '',
...     'owner_set-1-name': '',
... }
>>> formset = FormSet(data, instance=place)
>>> formset.is_valid()
True
>>> formset.save()
[<Owner: Joe Perry at Giordanos>]

>>> formset = FormSet(instance=place)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_owner_set-0-name">Name:</label> <input id="id_owner_set-0-name" type="text" name="owner_set-0-name" value="Joe Perry" maxlength="100" /><input type="hidden" name="owner_set-0-auto_id" value="1" id="id_owner_set-0-auto_id" /></p>
<p><label for="id_owner_set-1-name">Name:</label> <input id="id_owner_set-1-name" type="text" name="owner_set-1-name" maxlength="100" /><input type="hidden" name="owner_set-1-auto_id" id="id_owner_set-1-auto_id" /></p>
<p><label for="id_owner_set-2-name">Name:</label> <input id="id_owner_set-2-name" type="text" name="owner_set-2-name" maxlength="100" /><input type="hidden" name="owner_set-2-auto_id" id="id_owner_set-2-auto_id" /></p>

>>> data = {
...     'owner_set-TOTAL_FORMS': '3',
...     'owner_set-INITIAL_FORMS': '1',
...     'owner_set-0-auto_id': u'1',
...     'owner_set-0-name': u'Joe Perry',
...     'owner_set-1-auto_id': '',
...     'owner_set-1-name': u'Jack Berry',
...     'owner_set-2-auto_id': '',
...     'owner_set-2-name': '',
... }
>>> formset = FormSet(data, instance=place)
>>> formset.is_valid()
True
>>> formset.save()
[<Owner: Jack Berry at Giordanos>]

# Ensure a custom primary key that is a ForeignKey or OneToOneField get rendered for the user to choose.

>>> FormSet = modelformset_factory(OwnerProfile)
>>> formset = FormSet()
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_form-0-owner">Owner:</label> <select name="form-0-owner" id="id_form-0-owner">
<option value="" selected="selected">---------</option>
<option value="1">Joe Perry at Giordanos</option>
<option value="2">Jack Berry at Giordanos</option>
</select></p>
<p><label for="id_form-0-age">Age:</label> <input type="text" name="form-0-age" id="id_form-0-age" /></p>

>>> owner = Owner.objects.get(name=u'Joe Perry')
>>> FormSet = inlineformset_factory(Owner, OwnerProfile, max_num=1, can_delete=False)

>>> formset = FormSet(instance=owner)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_ownerprofile-0-age">Age:</label> <input type="text" name="ownerprofile-0-age" id="id_ownerprofile-0-age" /><input type="hidden" name="ownerprofile-0-owner" id="id_ownerprofile-0-owner" /></p>

>>> data = {
...     'ownerprofile-TOTAL_FORMS': '1',
...     'ownerprofile-INITIAL_FORMS': '0',
...     'ownerprofile-0-owner': '',
...     'ownerprofile-0-age': u'54',
... }
>>> formset = FormSet(data, instance=owner)
>>> formset.is_valid()
True
>>> formset.save()
[<OwnerProfile: Joe Perry is 54>]

>>> formset = FormSet(instance=owner)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_ownerprofile-0-age">Age:</label> <input type="text" name="ownerprofile-0-age" value="54" id="id_ownerprofile-0-age" /><input type="hidden" name="ownerprofile-0-owner" value="1" id="id_ownerprofile-0-owner" /></p>

>>> data = {
...     'ownerprofile-TOTAL_FORMS': '1',
...     'ownerprofile-INITIAL_FORMS': '1',
...     'ownerprofile-0-owner': u'1',
...     'ownerprofile-0-age': u'55',
... }
>>> formset = FormSet(data, instance=owner)
>>> formset.is_valid()
True
>>> formset.save()
[<OwnerProfile: Joe Perry is 55>]

# ForeignKey with unique=True should enforce max_num=1 

>>> FormSet = inlineformset_factory(Place, Location, can_delete=False)
>>> formset = FormSet(instance=place)
>>> for form in formset.forms:
...     print form.as_p()
<p><label for="id_location_set-0-lat">Lat:</label> <input id="id_location_set-0-lat" type="text" name="location_set-0-lat" maxlength="100" /></p>
<p><label for="id_location_set-0-lon">Lon:</label> <input id="id_location_set-0-lon" type="text" name="location_set-0-lon" maxlength="100" /><input type="hidden" name="location_set-0-id" id="id_location_set-0-id" /></p>

# Foreign keys in parents ########################################

>>> from django.forms.models import _get_foreign_key

>>> type(_get_foreign_key(Restaurant, Owner))
<class 'django.db.models.fields.related.ForeignKey'>
>>> type(_get_foreign_key(MexicanRestaurant, Owner))
<class 'django.db.models.fields.related.ForeignKey'>

"""}