Added nested included serializer support for remapped relations (django-json-api#347)

* Added nested included serializer support for remapped relations

* Added docstring to extract_relation_instance

Author: sliverc

CHANGELOG.md

@@ -7,6 +7,7 @@ v2.3.0
 * Fix for apps that don't use `django.contrib.contenttypes`.
 * Fix `resource_name` support for POST requests and nested serializers
 * Enforcing flake8 linting
+* Added nested included serializer support for remapped relations
 
 v2.2.0
 

example/serializers.py

@@ -111,10 +111,25 @@ class Meta:
         fields = ('name', 'email', 'bio', 'entries')
 
 
+class WriterSerializer(serializers.ModelSerializer):
+    included_serializers = {
+        'bio': AuthorBioSerializer
+    }
+
+    class Meta:
+        model = Author
+        fields = ('name', 'email', 'bio')
+        resource_name = 'writers'
+
+
 class CommentSerializer(serializers.ModelSerializer):
+    # testing remapping of related name
+    writer = relations.ResourceRelatedField(source='author', read_only=True)
+
     included_serializers = {
         'entry': EntrySerializer,
-        'author': AuthorSerializer
+        'author': AuthorSerializer,
+        'writer': WriterSerializer
     }
 
     class Meta:

example/tests/integration/test_includes.py

@@ -82,14 +82,15 @@ def test_missing_field_not_included(author_bio_factory, author_factory, client):
 
 def test_deep_included_data_on_list(multiple_entries, client):
     response = client.get(reverse("entry-list") + '?include=comments,comments.author,'
-                          'comments.author.bio&page_size=5')
+                          'comments.author.bio,comments.writer&page_size=5')
     included = load_json(response.content).get('included')
 
     assert len(load_json(response.content)['data']) == len(multiple_entries), (
         'Incorrect entry count'
     )
     assert [x.get('type') for x in included] == [
-        'authorBios', 'authorBios', 'authors', 'authors', 'comments', 'comments'
+        'authorBios', 'authorBios', 'authors', 'authors',
+        'comments', 'comments', 'writers', 'writers'
     ], 'List included types are incorrect'
 
     comment_count = len([resource for resource in included if resource["type"] == "comments"])
@@ -106,6 +107,13 @@ def test_deep_included_data_on_list(multiple_entries, client):
         author__bio__isnull=False).count() for entry in multiple_entries])
     assert author_bio_count == expected_author_bio_count, 'List author bio count is incorrect'
 
+    writer_count = len(
+        [resource for resource in included if resource["type"] == "writers"]
+    )
+    expected_writer_count = sum(
+        [entry.comments.filter(author__isnull=False).count() for entry in multiple_entries])
+    assert writer_count == expected_writer_count, 'List writer count is incorrect'
+
     # Also include entry authors
     response = client.get(reverse("entry-list") + '?include=authors,comments,comments.author,'
                           'comments.author.bio&page_size=5')

example/tests/test_serializers.py

@@ -102,6 +102,12 @@ def test_model_serializer_with_implicit_fields(self, comment, client):
                             "id": str(comment.author.pk)
                         }
                     },
+                    "writer": {
+                        "data": {
+                            "type": "writers",
+                            "id": str(comment.author.pk)
+                        }
+                    },
                 }
             }
         }

rest_framework_json_api/renderers.py

@@ -272,6 +272,36 @@ def extract_relationships(cls, fields, resource, resource_instance):
 
         return utils.format_keys(data)
 
+    @classmethod
+    def extract_relation_instance(cls, field_name, field, resource_instance, serializer):
+        """
+        Determines what instance represents given relation and extracts it.
+
+        Relation instance is determined by given field_name or source configured on
+        field. As fallback is a serializer method called with name of field's source.
+        """
+        relation_instance = None
+
+        try:
+            relation_instance = getattr(resource_instance, field_name)
+        except AttributeError:
+            try:
+                # For ManyRelatedFields if `related_name` is not set
+                # we need to access `foo_set` from `source`
+                relation_instance = getattr(resource_instance, field.child_relation.source)
+            except AttributeError:
+                if hasattr(serializer, field.source):
+                    serializer_method = getattr(serializer, field.source)
+                    relation_instance = serializer_method(resource_instance)
+                else:
+                    # case when source is a simple remap on resource_instance
+                    try:
+                        relation_instance = getattr(resource_instance, field.source)
+                    except AttributeError:
+                        pass
+
+        return relation_instance
+
     @classmethod
     def extract_included(cls, fields, resource, resource_instance, included_resources):
         # this function may be called with an empty record (example: Browsable Interface)
@@ -304,19 +334,9 @@ def extract_included(cls, fields, resource, resource_instance, included_resource
                 if field_name not in [node.split('.')[0] for node in included_resources]:
                     continue
 
-            try:
-                relation_instance = getattr(resource_instance, field_name)
-            except AttributeError:
-                try:
-                    # For ManyRelatedFields if `related_name` is not set we need to access `foo_set`
-                    # from `source`
-                    relation_instance = getattr(resource_instance, field.child_relation.source)
-                except AttributeError:
-                    if not hasattr(current_serializer, field.source):
-                        continue
-                    serializer_method = getattr(current_serializer, field.source)
-                    relation_instance = serializer_method(resource_instance)
-
+            relation_instance = cls.extract_relation_instance(
+                field_name, field, resource_instance, current_serializer
+            )
             if isinstance(relation_instance, Manager):
                 relation_instance = relation_instance.all()