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from __future__ import unicode_literals
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.generic import GenericRelation, GenericForeignKey
from django.db import models
from django.test import TestCase
from rest_framework import serializers
from rest_framework.compat import python_2_unicode_compatible
@python_2_unicode_compatible
class Tag(models.Model):
"""
Tags have a descriptive slug, and are attached to an arbitrary object.
"""
tag = models.SlugField()
content_type = models.ForeignKey(ContentType)
object_id = models.PositiveIntegerField()
tagged_item = GenericForeignKey('content_type', 'object_id')
def __str__(self):
return self.tag
@python_2_unicode_compatible
class Bookmark(models.Model):
"""
A URL bookmark that may have multiple tags attached.
"""
url = models.URLField()
tags = GenericRelation(Tag)
def __str__(self):
return 'Bookmark: %s' % self.url
@python_2_unicode_compatible
class Note(models.Model):
"""
A textual note that may have multiple tags attached.
"""
text = models.TextField()
tags = GenericRelation(Tag)
def __str__(self):
return 'Note: %s' % self.text
class TestGenericRelations(TestCase):
def setUp(self):
self.bookmark = Bookmark.objects.create(url='https://www.djangoproject.com/')
Tag.objects.create(tagged_item=self.bookmark, tag='django')
Tag.objects.create(tagged_item=self.bookmark, tag='python')
self.note = Note.objects.create(text='Remember the milk')
Tag.objects.create(tagged_item=self.note, tag='reminder')
def test_generic_relation(self):
"""
Test a relationship that spans a GenericRelation field.
IE. A reverse generic relationship.
"""
class BookmarkSerializer(serializers.ModelSerializer):
tags = serializers.StringRelatedField(many=True)
class Meta:
model = Bookmark
fields = ('tags', 'url')
serializer = BookmarkSerializer(self.bookmark)
expected = {
'tags': ['django', 'python'],
'url': 'https://www.djangoproject.com/'
}
self.assertEqual(serializer.data, expected)
def test_generic_fk(self):
"""
Test a relationship that spans a GenericForeignKey field.
IE. A forward generic relationship.
"""
class TagSerializer(serializers.ModelSerializer):
tagged_item = serializers.StringRelatedField()
class Meta:
model = Tag
fields = ('tag', 'tagged_item')
serializer = TagSerializer(Tag.objects.all(), many=True)
expected = [
{
'tag': 'django',
'tagged_item': 'Bookmark: https://www.djangoproject.com/'
},
{
'tag': 'python',
'tagged_item': 'Bookmark: https://www.djangoproject.com/'
},
{
'tag': 'reminder',
'tagged_item': 'Note: Remember the milk'
}
]
self.assertEqual(serializer.data, expected)
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