1 """

     2 10. One-to-one relationships

     3 

     4 To define a one-to-one relationship, use ``OneToOneField()``.

     5 

     6 In this example, a ``Place`` optionally can be a ``Restaurant``.

     7 """

     8 

     9 from django.db import models, transaction, IntegrityError

    10 

    11 class Place(models.Model):

    12     name = models.CharField(max_length=50)

    13     address = models.CharField(max_length=80)

    14 

    15     def __unicode__(self):

    16         return u"%s the place" % self.name

    17 

    18 class Restaurant(models.Model):

    19     place = models.OneToOneField(Place, primary_key=True)

    20     serves_hot_dogs = models.BooleanField()

    21     serves_pizza = models.BooleanField()

    22 

    23     def __unicode__(self):

    24         return u"%s the restaurant" % self.place.name

    25 

    26 class Waiter(models.Model):

    27     restaurant = models.ForeignKey(Restaurant)

    28     name = models.CharField(max_length=50)

    29 

    30     def __unicode__(self):

    31         return u"%s the waiter at %s" % (self.name, self.restaurant)

    32 

    33 class ManualPrimaryKey(models.Model):

    34     primary_key = models.CharField(max_length=10, primary_key=True)

    35     name = models.CharField(max_length = 50)

    36 

    37 class RelatedModel(models.Model):

    38     link = models.OneToOneField(ManualPrimaryKey)

    39     name = models.CharField(max_length = 50)

    40 

    41 class MultiModel(models.Model):

    42     link1 = models.OneToOneField(Place)

    43     link2 = models.OneToOneField(ManualPrimaryKey)

    44     name = models.CharField(max_length=50)

    45 

    46     def __unicode__(self):

    47         return u"Multimodel %s" % self.name