--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/thirdparty/google_appengine/lib/django/tests/modeltests/generic_relations/models.py	Tue Aug 26 21:49:54 2008 +0000
@@ -0,0 +1,134 @@
+"""
+34. Generic relations
+
+Generic relations let an object have a foreign key to any object through a
+content-type/object-id field. A generic foreign key 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 django.db import models
+from django.contrib.contenttypes.models import ContentType
+
+class TaggedItem(models.Model):
+    """A tag on an item."""
+    tag = models.SlugField()
+    content_type = models.ForeignKey(ContentType)
+    object_id = models.PositiveIntegerField()
+    
+    content_object = models.GenericForeignKey()
+    
+    class Meta:
+        ordering = ["tag"]
+    
+    def __str__(self):
+        return self.tag
+
+class Animal(models.Model):
+    common_name = models.CharField(maxlength=150)
+    latin_name = models.CharField(maxlength=150)
+    
+    tags = models.GenericRelation(TaggedItem)
+
+    def __str__(self):
+        return self.common_name
+        
+class Vegetable(models.Model):
+    name = models.CharField(maxlength=150)
+    is_yucky = models.BooleanField(default=True)
+    
+    tags = models.GenericRelation(TaggedItem)
+    
+    def __str__(self):
+        return self.name
+    
+class Mineral(models.Model):
+    name = models.CharField(maxlength=150)
+    hardness = models.PositiveSmallIntegerField()
+    
+    # note the lack of an explicit GenericRelation here...
+    
+    def __str__(self):
+        return self.name
+        
+__test__ = {'API_TESTS':"""
+# Create the world in 7 lines of code...
+>>> lion = Animal(common_name="Lion", latin_name="Panthera leo")
+>>> platypus = Animal(common_name="Platypus", latin_name="Ornithorhynchus anatinus")
+>>> eggplant = Vegetable(name="Eggplant", is_yucky=True)
+>>> bacon = Vegetable(name="Bacon", is_yucky=False)
+>>> quartz = Mineral(name="Quartz", hardness=7)
+>>> for o in (lion, platypus, eggplant, bacon, quartz):
+...     o.save()
+
+# Objects with declared GenericRelations can be tagged directly -- the API
+# mimics the many-to-many API.
+>>> bacon.tags.create(tag="fatty")
+<TaggedItem: fatty>
+>>> bacon.tags.create(tag="salty")
+<TaggedItem: salty>
+>>> lion.tags.create(tag="yellow")
+<TaggedItem: yellow>
+>>> lion.tags.create(tag="hairy")
+<TaggedItem: hairy>
+
+>>> lion.tags.all()
+[<TaggedItem: hairy>, <TaggedItem: yellow>]
+>>> bacon.tags.all()
+[<TaggedItem: fatty>, <TaggedItem: salty>]
+
+# You can easily access the content object like a foreign key.
+>>> t = TaggedItem.objects.get(tag="salty")
+>>> t.content_object
+<Vegetable: Bacon>
+
+# Recall that the Mineral class doesn't have an explicit GenericRelation
+# defined. That's OK, because you can create TaggedItems explicitly.
+>>> tag1 = TaggedItem(content_object=quartz, tag="shiny")
+>>> tag2 = TaggedItem(content_object=quartz, tag="clearish")
+>>> tag1.save()
+>>> tag2.save()
+
+# However, excluding GenericRelations means your lookups have to be a bit more
+# explicit.
+>>> from django.contrib.contenttypes.models import ContentType
+>>> ctype = ContentType.objects.get_for_model(quartz)
+>>> TaggedItem.objects.filter(content_type__pk=ctype.id, object_id=quartz.id)
+[<TaggedItem: clearish>, <TaggedItem: shiny>]
+
+# You can set a generic foreign key in the way you'd expect.
+>>> tag1.content_object = platypus
+>>> tag1.save()
+>>> platypus.tags.all()
+[<TaggedItem: shiny>]
+>>> TaggedItem.objects.filter(content_type__pk=ctype.id, object_id=quartz.id)
+[<TaggedItem: clearish>]
+
+# If you delete an object with an explicit Generic relation, the related
+# objects are deleted when the source object is deleted.
+# Original list of tags:
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()]
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('hairy', <ContentType: animal>, 1), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2), ('yellow', <ContentType: animal>, 1)]
+
+>>> lion.delete()
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()]
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+
+# If Generic Relation is not explicitly defined, any related objects 
+# remain after deletion of the source object.
+>>> quartz.delete()
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()]
+[('clearish', <ContentType: mineral>, 1), ('fatty', <ContentType: vegetable>, 2), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+
+# If you delete a tag, the objects using the tag are unaffected 
+# (other than losing a tag)
+>>> tag = TaggedItem.objects.get(id=1)
+>>> tag.delete()
+>>> bacon.tags.all()
+[<TaggedItem: salty>]
+>>> [(t.tag, t.content_type, t.object_id) for t in TaggedItem.objects.all()]
+[('clearish', <ContentType: mineral>, 1), ('salty', <ContentType: vegetable>, 2), ('shiny', <ContentType: animal>, 2)]
+
+"""}