mirror of
https://github.com/django/django.git
synced 2024-11-19 07:54:07 +00:00
d4a0b27838
* Renamed the __unicode__ methods * Applied the python_2_unicode_compatible decorator * Removed the StrAndUnicode mix-in that is superseded by python_2_unicode_compatible * Kept the __unicode__ methods in classes that specifically test it under Python 2
97 lines
2.9 KiB
Python
97 lines
2.9 KiB
Python
"""
|
|
34. Generic relations
|
|
|
|
Generic relations let an object have a foreign key to any object through a
|
|
content-type/object-id field. A ``GenericForeignKey`` field can point to any
|
|
object, be it animal, vegetable, or mineral.
|
|
|
|
The canonical example is tags (although this example implementation is *far*
|
|
from complete).
|
|
"""
|
|
|
|
from __future__ import unicode_literals
|
|
|
|
from django.contrib.contenttypes import generic
|
|
from django.contrib.contenttypes.models import ContentType
|
|
from django.db import models
|
|
from django.utils.encoding import python_2_unicode_compatible
|
|
|
|
|
|
@python_2_unicode_compatible
|
|
class TaggedItem(models.Model):
|
|
"""A tag on an item."""
|
|
tag = models.SlugField()
|
|
content_type = models.ForeignKey(ContentType)
|
|
object_id = models.PositiveIntegerField()
|
|
|
|
content_object = generic.GenericForeignKey()
|
|
|
|
class Meta:
|
|
ordering = ["tag", "content_type__name"]
|
|
|
|
def __str__(self):
|
|
return self.tag
|
|
|
|
class ValuableTaggedItem(TaggedItem):
|
|
value = models.PositiveIntegerField()
|
|
|
|
@python_2_unicode_compatible
|
|
class Comparison(models.Model):
|
|
"""
|
|
A model that tests having multiple GenericForeignKeys
|
|
"""
|
|
comparative = models.CharField(max_length=50)
|
|
|
|
content_type1 = models.ForeignKey(ContentType, related_name="comparative1_set")
|
|
object_id1 = models.PositiveIntegerField()
|
|
|
|
content_type2 = models.ForeignKey(ContentType, related_name="comparative2_set")
|
|
object_id2 = models.PositiveIntegerField()
|
|
|
|
first_obj = generic.GenericForeignKey(ct_field="content_type1", fk_field="object_id1")
|
|
other_obj = generic.GenericForeignKey(ct_field="content_type2", fk_field="object_id2")
|
|
|
|
def __str__(self):
|
|
return "%s is %s than %s" % (self.first_obj, self.comparative, self.other_obj)
|
|
|
|
@python_2_unicode_compatible
|
|
class Animal(models.Model):
|
|
common_name = models.CharField(max_length=150)
|
|
latin_name = models.CharField(max_length=150)
|
|
|
|
tags = generic.GenericRelation(TaggedItem)
|
|
comparisons = generic.GenericRelation(Comparison,
|
|
object_id_field="object_id1",
|
|
content_type_field="content_type1")
|
|
|
|
def __str__(self):
|
|
return self.common_name
|
|
|
|
@python_2_unicode_compatible
|
|
class Vegetable(models.Model):
|
|
name = models.CharField(max_length=150)
|
|
is_yucky = models.BooleanField(default=True)
|
|
|
|
tags = generic.GenericRelation(TaggedItem)
|
|
|
|
def __str__(self):
|
|
return self.name
|
|
|
|
@python_2_unicode_compatible
|
|
class Mineral(models.Model):
|
|
name = models.CharField(max_length=150)
|
|
hardness = models.PositiveSmallIntegerField()
|
|
|
|
# note the lack of an explicit GenericRelation here...
|
|
|
|
def __str__(self):
|
|
return self.name
|
|
|
|
class GeckoManager(models.Manager):
|
|
def get_query_set(self):
|
|
return super(GeckoManager, self).get_query_set().filter(has_tail=True)
|
|
|
|
class Gecko(models.Model):
|
|
has_tail = models.BooleanField()
|
|
objects = GeckoManager()
|