mirror of
https://github.com/django/django.git
synced 2024-12-27 11:35:53 +00:00
473306a658
git-svn-id: http://code.djangoproject.com/svn/django/trunk@648 bcc190cf-cafb-0310-a4f2-bffc1f526a37
78 lines
2.1 KiB
Python
78 lines
2.1 KiB
Python
"""
|
|
10. One-to-one relationships
|
|
|
|
To define a one-to-one relationship, use ``OneToOneField()``.
|
|
|
|
In this example, a ``Place`` optionally can be a ``Restaurant``.
|
|
"""
|
|
|
|
from django.core import meta
|
|
|
|
class Place(meta.Model):
|
|
name = meta.CharField(maxlength=50)
|
|
address = meta.CharField(maxlength=80)
|
|
|
|
def __repr__(self):
|
|
return "%s the place" % self.name
|
|
|
|
class Restaurant(meta.Model):
|
|
place = meta.OneToOneField(Place)
|
|
serves_hot_dogs = meta.BooleanField()
|
|
serves_pizza = meta.BooleanField()
|
|
|
|
def __repr__(self):
|
|
return "%s the restaurant" % self.get_place().name
|
|
|
|
class Waiter(meta.Model):
|
|
restaurant = meta.ForeignKey(Restaurant)
|
|
name = meta.CharField(maxlength=50)
|
|
|
|
def __repr__(self):
|
|
return "%s the waiter at %s" % (self.name, self.get_restaurant())
|
|
|
|
API_TESTS = """
|
|
# Create a couple of Places.
|
|
>>> p1 = places.Place(name='Demon Dogs', address='944 W. Fullerton')
|
|
>>> p1.save()
|
|
>>> p2 = places.Place(name='Ace Hardware', address='1013 N. Ashland')
|
|
>>> p2.save()
|
|
|
|
# Create a Restaurant. Pass the ID of the "parent" object as this object's ID.
|
|
>>> r = restaurants.Restaurant(place=p1, serves_hot_dogs=True, serves_pizza=False)
|
|
>>> r.save()
|
|
|
|
# A Restaurant can access its place.
|
|
>>> r.get_place()
|
|
Demon Dogs the place
|
|
|
|
# A Place can access its restaurant, if available.
|
|
>>> p1.get_restaurant()
|
|
Demon Dogs the restaurant
|
|
|
|
# p2 doesn't have an associated restaurant.
|
|
>>> p2.get_restaurant()
|
|
Traceback (most recent call last):
|
|
...
|
|
RestaurantDoesNotExist: Restaurant does not exist for {'place__id__exact': ...}
|
|
|
|
# restaurants.get_list() just returns the Restaurants, not the Places.
|
|
>>> restaurants.get_list()
|
|
[Demon Dogs the restaurant]
|
|
|
|
# places.get_list() returns all Places, regardless of whether they have
|
|
# Restaurants.
|
|
>>> places.get_list(order_by=['name'])
|
|
[Ace Hardware the place, Demon Dogs the place]
|
|
|
|
>>> restaurants.get_object(place__id__exact=1)
|
|
Demon Dogs the restaurant
|
|
>>> restaurants.get_object(pk=1)
|
|
Demon Dogs the restaurant
|
|
|
|
# Add a Waiter to the Restaurant.
|
|
>>> w = r.add_waiter(name='Joe')
|
|
>>> w.save()
|
|
>>> w
|
|
Joe the waiter at Demon Dogs the restaurant
|
|
"""
|