"""

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.db import models, transaction, IntegrityError

class Place(models.Model):

    name = models.CharField(max_length=50)

    address = models.CharField(max_length=80)

    def __unicode__(self):

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

class Restaurant(models.Model):

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

    serves_hot_dogs = models.BooleanField()

    serves_pizza = models.BooleanField()

    def __unicode__(self):

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

class Waiter(models.Model):

    restaurant = models.ForeignKey(Restaurant)

    name = models.CharField(max_length=50)

    def __unicode__(self):

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

class ManualPrimaryKey(models.Model):

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

    name = models.CharField(max_length = 50)

class RelatedModel(models.Model):

    link = models.OneToOneField(ManualPrimaryKey)

    name = models.CharField(max_length = 50)

class MultiModel(models.Model):

    link1 = models.OneToOneField(Place)

    link2 = models.OneToOneField(ManualPrimaryKey)

    name = models.CharField(max_length=50)

    def __unicode__(self):

        return u"Multimodel %s" % self.name