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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
try:
from django.utils.encoding import python_2_unicode_compatible
except ImportError:
def python_2_unicode_compatible(klass):
"""
A decorator that defines __unicode__ and __str__ methods under Python 2.
Under Python 3 it does nothing.
To support Python 2 and 3 with a single code base, define a __str__ method
returning text and apply this decorator to the class.
"""
if '__str__' not in klass.__dict__:
raise ValueError("@python_2_unicode_compatible cannot be applied "
"to %s because it doesn't define __str__()." %
klass.__name__)
klass.__unicode__ = klass.__str__
klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
return klass
@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.RelatedField(many=True)
class Meta:
model = Bookmark
exclude = ('id',)
serializer = BookmarkSerializer(self.bookmark)
expected = {
'tags': ['django', 'python'],
'url': 'https://www.djangoproject.com/'
}
self.assertEqual(serializer.data, expected)
def test_generic_nested_relation(self):
"""
Test saving a GenericRelation field via a nested serializer.
"""
class TagSerializer(serializers.ModelSerializer):
class Meta:
model = Tag
exclude = ('content_type', 'object_id')
class BookmarkSerializer(serializers.ModelSerializer):
tags = TagSerializer()
class Meta:
model = Bookmark
exclude = ('id',)
data = {
'url': 'https://docs.djangoproject.com/',
'tags': [
{'tag': 'contenttypes'},
{'tag': 'genericrelations'},
]
}
serializer = BookmarkSerializer(data=data)
self.assertTrue(serializer.is_valid())
serializer.save()
self.assertEqual(serializer.object.tags.count(), 2)
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.RelatedField()
class Meta:
model = Tag
exclude = ('id', 'content_type', 'object_id')
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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