Add test to demonstrate that nested add/remove order needs addressing

tests/models.py

@@ -1,5 +1,6 @@
 from __future__ import unicode_literals
 from django.db import models
+from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 from rest_framework import serializers
 
@@ -103,6 +104,10 @@ class Person(RESTFrameworkModel):
 class BlogPost(RESTFrameworkModel):
     title = models.CharField(max_length=100)
     writer = models.ForeignKey(Person, null=True, blank=True)
+    created = models.DateTimeField(default=now)
+
+    class Meta:
+        unique_together = [('writer', 'title')]
 
     def get_first_comment(self):
         return self.blogpostcomment_set.all()[0]

tests/test_serializer.py

@@ -1448,7 +1448,7 @@ class DepthTest(TestCase):
     def test_implicit_nesting(self):
 
         writer = Person.objects.create(name="django", age=1)
-        post = BlogPost.objects.create(title="Test blog post", writer=writer)
+        post = BlogPost.objects.create(title="Test blog post", writer=writer, created=datetime.datetime(1970, 1, 1))
         comment = BlogPostComment.objects.create(text="Test blog post comment", blog_post=post)
 
         class BlogPostCommentSerializer(serializers.ModelSerializer):
@@ -1458,7 +1458,7 @@ class DepthTest(TestCase):
 
         serializer = BlogPostCommentSerializer(instance=comment)
         expected = {'id': 1, 'text': 'Test blog post comment', 'blog_post': {'id': 1, 'title': 'Test blog post',
-                    'writer': {'id': 1, 'name': 'django', 'age': 1}}}
+                    'created': datetime.datetime(1970, 1, 1), 'writer': {'id': 1, 'name': 'django', 'age': 1}}}
 
         self.assertEqual(serializer.data, expected)
 
@@ -1476,6 +1476,7 @@ class DepthTest(TestCase):
 
             class Meta:
                 model = BlogPost
+                exclude = ('created',)
 
         class BlogPostCommentSerializer(serializers.ModelSerializer):
             blog_post = BlogPostSerializer()

tests/test_serializer_nested.py

@@ -347,3 +347,45 @@ class NestedModelSerializerUpdateTests(TestCase):
         result = deserialize.object
         result.save()
         self.assertEqual(result.id, john.id)
+
+    def test_remove_nested_before_adding(self):
+        john = models.Person.objects.create(name="john")
+
+        post = john.blogpost_set.create(title="Test blog post")
+        post.blogpostcomment_set.create(text="I hate this blog post")
+        post.blogpostcomment_set.create(text="I love this blog post")
+
+        class BlogPostCommentSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = models.BlogPostComment
+                exclude = ('blog_post',)
+
+        class BlogPostSerializer(serializers.ModelSerializer):
+            comments = BlogPostCommentSerializer(many=True, source='blogpostcomment_set')
+
+            class Meta:
+                model = models.BlogPost
+                fields = ('id', 'title', 'comments')
+
+        class PersonSerializer(serializers.ModelSerializer):
+            posts = BlogPostSerializer(many=True, source='blogpost_set', allow_add_remove=True)
+
+            class Meta:
+                model = models.Person
+                fields = ('id', 'name', 'age', 'posts')
+
+        serialize = PersonSerializer(instance=john)
+
+        # Remove the ID from John's post so that it is no longer the same post.
+        john_data = serialize.data
+        self.assertEqual(len(john_data['posts']), 1)
+        del john_data['posts'][0]['id']
+
+        deserialize = PersonSerializer(data=john_data, instance=john)
+        self.assertTrue(deserialize.is_valid(), deserialize.errors)
+
+        deserialize.save()
+        result = deserialize.object
+        self.assertEqual(result.id, john.id)
+        self.assertEqual(result.blogpost_set.count(), 1)
+        self.assertNotEqual(result.blogpost_set.all()[0].created, post.created)