from copy import deepcopy
from django.db import models
from django.test import TestCase
from rest_framework import serializers


# ForeignKey

class ForeignKeyTarget(models.Model):
    name = models.CharField(max_length=100)


class ForeignKeySource(models.Model):
    name = models.CharField(max_length=100)
    target = models.ForeignKey(ForeignKeyTarget, related_name='sources')


class ForeignKeySourceSerializer(serializers.ModelSerializer):
    class Meta:
        model = ForeignKeySource


class ForeignKeyTargetSerializer(serializers.ModelSerializer):
    sources = ForeignKeySourceSerializer()

    class Meta:
        model = ForeignKeyTarget


class ReverseForeignKeyTests(TestCase):
    def setUp(self):
        target = ForeignKeyTarget(name='target-1')
        target.save()
        new_target = ForeignKeyTarget(name='target-2')
        new_target.save()
        for idx in range(1, 4):
            source = ForeignKeySource(name='source-%d' % idx, target=target)
            source.save()
        self.target_data = {'id': 1, 'name': u'target-1', 'sources': [
                {'id': 1, 'name': u'source-1', 'target': 1},
                {'id': 2, 'name': u'source-2', 'target': 1},
                {'id': 3, 'name': u'source-3', 'target': 1},
            ]}
        self.new_target_data = {'id': 2, 'name': u'target-2', 'sources': []}
        self.data = [self.target_data, self.new_target_data]

    def test_reverse_foreign_key_retrieve(self):
        queryset = ForeignKeyTarget.objects.all()
        serializer = ForeignKeyTargetSerializer(queryset)
        self.assertEquals(serializer.data, self.data)

    def test_reverse_foreign_key_update(self):
        data = deepcopy(self.target_data)
        data['sources'][0]['name'] = 'source-1-changed'
        data['sources'][2]['name'] = 'source-3-changed'
        instance = ForeignKeyTarget.objects.get(pk=1)
        serializer = ForeignKeyTargetSerializer(instance, data=data)
        self.assertTrue(serializer.is_valid())
        self.assertEquals(serializer.data, data)
        serializer.save()

        # Ensure target 1 is updated, and everything else is as expected
        queryset = ForeignKeyTarget.objects.all()
        serializer = ForeignKeyTargetSerializer(queryset)
        expected = deepcopy(self.data)
        expected[0]['sources'][0]['name'] = 'source-1-changed'
        expected[0]['sources'][2]['name'] = 'source-3-changed'
        self.assertEquals(serializer.data, expected)

Add tests for retrieving/updating reverse fks
Add tests for retrieving/updating reverse fks
