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