Polymorphism improvements

.gitignore

@@ -30,6 +30,8 @@ pip-delete-this-directory.txt
 
 # Tox
 .tox/
+.cache/
+.python-version
 
 # VirtualEnv
 .venv/

docs/usage.md

@@ -375,7 +375,7 @@ class LineItemViewSet(viewsets.ModelViewSet):
 
 ### RelationshipView
 `rest_framework_json_api.views.RelationshipView` is used to build
-relationship views (see the 
+relationship views (see the
 [JSON API spec](http://jsonapi.org/format/#fetching-relationships)).
 The `self` link on a relationship object should point to the corresponding
 relationship view.
@@ -425,7 +425,9 @@ field_name_mapping = {
 
 ### Working with polymorphic resources
 
-This package can defer the resolution of the type of polymorphic models instances to get the appropriate type.
+#### Extraction of the polymorphic type
+
+This package can defer the resolution of the type of polymorphic models instances to retrieve the appropriate type.
 However, most models are not polymorphic and for performance reasons this is only done if the underlying model is a subclass of a polymorphic model.
 
 Polymorphic ancestors must be defined on settings like this:
@@ -436,6 +438,48 @@ JSON_API_POLYMORPHIC_ANCESTORS = (
 )
 ```
 
+#### Writing polymorphic resources
+
+A polymorphic endpoint can be setup if associated with a polymorphic serializer.
+A polymorphic serializer take care of (de)serializing the correct instances types and can be defined like this:
+
+```python
+class ProjectSerializer(serializers.PolymorphicModelSerializer):
+    polymorphic_serializers = [ArtProjectSerializer, ResearchProjectSerializer]
+
+    class Meta:
+        model = models.Project
+```
+
+It must inherit from `serializers.PolymorphicModelSerializer` and define the `polymorphic_serializers` list.
+This attribute defines the accepted resource types.
+
+
+Polymorphic relations can also be handled with `relations.PolymorphicResourceRelatedField` like this:
+
+```python
+class CompanySerializer(serializers.ModelSerializer):
+    current_project = relations.PolymorphicResourceRelatedField(
+        ProjectSerializer, queryset=models.Project.objects.all())
+    future_projects = relations.PolymorphicResourceRelatedField(
+        ProjectSerializer, queryset=models.Project.objects.all(), many=True)
+
+    class Meta:
+        model = models.Company
+```
+
+They must be explicitely declared with the `polymorphic_serializer` (first positional argument) correctly defined.
+It must be a subclass of `serializers.PolymorphicModelSerializer`.
+
+<div class="warning">
+    <strong>Note:</strong>
+    Polymorphic resources are not compatible with
+    <code class="docutils literal">
+        <span class="pre">resource_name</span>
+    </code>
+    defined on the view.
+</div>
+
 ### Meta
 
 You may add metadata to the rendered json in two different ways: `meta_fields` and `get_root_meta`.

example/migrations/0002_auto_20160513_0857.py

@@ -1,17 +1,26 @@
 # -*- coding: utf-8 -*-
 # Generated by Django 1.9.6 on 2016-05-13 08:57
 from __future__ import unicode_literals
+from distutils.version import LooseVersion
 
 from django.db import migrations, models
 import django.db.models.deletion
+import django
 
 
 class Migration(migrations.Migration):
 
-    dependencies = [
-        ('contenttypes', '0002_remove_content_type_name'),
-        ('example', '0001_initial'),
-    ]
+    # TODO: Must be removed as soon as Django 1.7 support is dropped
+    if django.get_version() < LooseVersion('1.8'):
+        dependencies = [
+            ('contenttypes', '0001_initial'),
+            ('example', '0001_initial'),
+        ]
+    else:
+        dependencies = [
+            ('contenttypes', '0002_remove_content_type_name'),
+            ('example', '0001_initial'),
+        ]
 
     operations = [
         migrations.CreateModel(

example/serializers.py

@@ -1,7 +1,5 @@
 from datetime import datetime
-from django.db.models.query import QuerySet
-from rest_framework.utils.serializer_helpers import BindingDict
-from rest_framework_json_api import serializers, relations, utils
+from rest_framework_json_api import serializers, relations
 from example import models
 
 
@@ -40,15 +38,15 @@ def __init__(self, *args, **kwargs):
     }
 
     body_format = serializers.SerializerMethodField()
-    # many related from model
+    # Many related from model
     comments = relations.ResourceRelatedField(
-            source='comment_set', many=True, read_only=True)
-    # many related from serializer
+        source='comment_set', many=True, read_only=True)
+    # Many related from serializer
     suggested = relations.SerializerMethodResourceRelatedField(
-            source='get_suggested', model=models.Entry, many=True, read_only=True)
-    # single related from serializer
+        source='get_suggested', model=models.Entry, many=True, read_only=True)
+    # Single related from serializer
     featured = relations.SerializerMethodResourceRelatedField(
-            source='get_featured', model=models.Entry, read_only=True)
+        source='get_featured', model=models.Entry, read_only=True)
 
     def get_suggested(self, obj):
         return models.Entry.objects.exclude(pk=obj.pk)
@@ -107,53 +105,20 @@ class Meta:
         exclude = ('polymorphic_ctype',)
 
 
-class ProjectSerializer(serializers.ModelSerializer):
-
-    polymorphic_serializers = [
-        {'model': models.ArtProject, 'serializer': ArtProjectSerializer},
-        {'model': models.ResearchProject, 'serializer': ResearchProjectSerializer},
-    ]
+class ProjectSerializer(serializers.PolymorphicModelSerializer):
+    polymorphic_serializers = [ArtProjectSerializer, ResearchProjectSerializer]
 
     class Meta:
         model = models.Project
         exclude = ('polymorphic_ctype',)
 
-    def _get_actual_serializer_from_instance(self, instance):
-        for info in self.polymorphic_serializers:
-            if isinstance(instance, info.get('model')):
-                actual_serializer = info.get('serializer')
-                return actual_serializer(instance, context=self.context)
-
-    @property
-    def fields(self):
-        _fields = BindingDict(self)
-        for key, value in self.get_fields().items():
-            _fields[key] = value
-        return _fields
-
-    def get_fields(self):
-        if self.instance is not None:
-            if not isinstance(self.instance, QuerySet):
-                return self._get_actual_serializer_from_instance(self.instance).get_fields()
-            else:
-                raise Exception("Cannot get fields from a polymorphic serializer given a queryset")
-        return super(ProjectSerializer, self).get_fields()
-
-    def to_representation(self, instance):
-        # Handle polymorphism
-        return self._get_actual_serializer_from_instance(instance).to_representation(instance)
-
-    def to_internal_value(self, data):
-        data_type = data.get('type')
-        for info in self.polymorphic_serializers:
-            actual_serializer = info['serializer']
-            if data_type == utils.get_resource_type_from_serializer(actual_serializer):
-                self.__class__ = actual_serializer
-                return actual_serializer(data, context=self.context).to_internal_value(data)
-        raise Exception("Could not deserialize")
-
 
 class CompanySerializer(serializers.ModelSerializer):
+    current_project = relations.PolymorphicResourceRelatedField(
+        ProjectSerializer, queryset=models.Project.objects.all())
+    future_projects = relations.PolymorphicResourceRelatedField(
+        ProjectSerializer, queryset=models.Project.objects.all(), many=True)
+
     included_serializers = {
         'current_project': ProjectSerializer,
         'future_projects': ProjectSerializer,

example/tests/integration/test_polymorphism.py

@@ -29,13 +29,14 @@ def test_polymorphism_on_included_relations(single_company, client):
     assert content["data"]["relationships"]["currentProject"]["data"]["type"] == "artProjects"
     assert [rel["type"] for rel in content["data"]["relationships"]["futureProjects"]["data"]] == [
         "researchProjects", "artProjects"]
-    assert [x.get('type') for x in content.get('included')] == ['artProjects', 'artProjects', 'researchProjects'], \
-        'Detail included types are incorrect'
+    assert [x.get('type') for x in content.get('included')] == [
+        'artProjects', 'artProjects', 'researchProjects'], 'Detail included types are incorrect'
     # Ensure that the child fields are present.
     assert content.get('included')[0].get('attributes').get('artist') is not None
     assert content.get('included')[1].get('attributes').get('artist') is not None
     assert content.get('included')[2].get('attributes').get('supervisor') is not None
 
+
 def test_polymorphism_on_polymorphic_model_detail_patch(single_art_project, client):
     url = reverse("project-detail", kwargs={'pk': single_art_project.pk})
     response = client.get(url)
@@ -50,6 +51,7 @@ def test_polymorphism_on_polymorphic_model_detail_patch(single_art_project, clie
     assert new_content['data']['attributes']['topic'] == test_topic
     assert new_content['data']['attributes']['artist'] == test_artist
 
+
 def test_polymorphism_on_polymorphic_model_list_post(client):
     test_topic = 'New test topic {}'.format(random.randint(0, 999999))
     test_artist = 'test-{}'.format(random.randint(0, 999999))
@@ -69,3 +71,66 @@ def test_polymorphism_on_polymorphic_model_list_post(client):
     assert content["data"]["type"] == "artProjects"
     assert content['data']['attributes']['topic'] == test_topic
     assert content['data']['attributes']['artist'] == test_artist
+
+
+def test_invalid_type_on_polymorphic_model(client):
+    test_topic = 'New test topic {}'.format(random.randint(0, 999999))
+    test_artist = 'test-{}'.format(random.randint(0, 999999))
+    url = reverse('project-list')
+    data = {
+        'data': {
+            'type': 'invalidProjects',
+            'attributes': {
+                'topic': test_topic,
+                'artist': test_artist
+            }
+        }
+    }
+    response = client.post(url, data=json.dumps(data), content_type='application/vnd.api+json')
+    assert response.status_code == 409
+    content = load_json(response.content)
+    assert len(content["errors"]) is 1
+    assert content["errors"][0]["status"] == "409"
+    assert content["errors"][0]["detail"] == \
+        "The resource object's type (invalidProjects) is not the type that constitute the " \
+        "collection represented by the endpoint (one of [researchProjects, artProjects])."
+
+
+def test_polymorphism_relations_update(single_company, research_project_factory, client):
+    response = client.get(reverse("company-detail", kwargs={'pk': single_company.pk}))
+    content = load_json(response.content)
+    assert content["data"]["relationships"]["currentProject"]["data"]["type"] == "artProjects"
+
+    research_project = research_project_factory()
+    content["data"]["relationships"]["currentProject"]["data"] = {
+        "type": "researchProjects",
+        "id": research_project.pk
+    }
+    response = client.put(reverse("company-detail", kwargs={'pk': single_company.pk}),
+                          data=json.dumps(content), content_type='application/vnd.api+json')
+    assert response.status_code == 200
+    content = load_json(response.content)
+    assert content["data"]["relationships"]["currentProject"]["data"]["type"] == "researchProjects"
+    assert int(content["data"]["relationships"]["currentProject"]["data"]["id"]) == \
+        research_project.pk
+
+
+def test_invalid_type_on_polymorphic_relation(single_company, research_project_factory, client):
+    response = client.get(reverse("company-detail", kwargs={'pk': single_company.pk}))
+    content = load_json(response.content)
+    assert content["data"]["relationships"]["currentProject"]["data"]["type"] == "artProjects"
+
+    research_project = research_project_factory()
+    content["data"]["relationships"]["currentProject"]["data"] = {
+        "type": "invalidProjects",
+        "id": research_project.pk
+    }
+    response = client.put(reverse("company-detail", kwargs={'pk': single_company.pk}),
+                          data=json.dumps(content), content_type='application/vnd.api+json')
+    assert response.status_code == 409
+    content = load_json(response.content)
+    assert len(content["errors"]) is 1
+    assert content["errors"][0]["status"] == "409"
+    assert content["errors"][0]["detail"] == \
+        "Incorrect relation type. Expected one of [researchProjects, artProjects], " \
+        "received invalidProjects."

rest_framework_json_api/parsers.py

@@ -30,7 +30,8 @@ class JSONParser(parsers.JSONParser):
 
     @staticmethod
     def parse_attributes(data):
-        return utils.format_keys(data.get('attributes'), 'underscore') if data.get('attributes') else dict()
+        return utils.format_keys(
+            data.get('attributes'), 'underscore') if data.get('attributes') else dict()
 
     @staticmethod
     def parse_relationships(data):
@@ -51,40 +52,49 @@ def parse(self, stream, media_type=None, parser_context=None):
         """
         Parses the incoming bytestream as JSON and returns the resulting data
         """
-        result = super(JSONParser, self).parse(stream, media_type=media_type, parser_context=parser_context)
+        result = super(JSONParser, self).parse(
+            stream, media_type=media_type, parser_context=parser_context)
         data = result.get('data')
 
         if data:
             from rest_framework_json_api.views import RelationshipView
             if isinstance(parser_context['view'], RelationshipView):
-                # We skip parsing the object as JSONAPI Resource Identifier Object and not a regular Resource Object
+                # We skip parsing the object as JSONAPI Resource Identifier Object is not a
+                # regular Resource Object
                 if isinstance(data, list):
                     for resource_identifier_object in data:
-                        if not (resource_identifier_object.get('id') and resource_identifier_object.get('type')):
-                            raise ParseError(
-                                'Received data contains one or more malformed JSONAPI Resource Identifier Object(s)'
-                            )
+                        if not (resource_identifier_object.get('id') and
+                                resource_identifier_object.get('type')):
+                            raise ParseError('Received data contains one or more malformed '
+                                             'JSONAPI Resource Identifier Object(s)')
                 elif not (data.get('id') and data.get('type')):
-                    raise ParseError('Received data is not a valid JSONAPI Resource Identifier Object')
+                    raise ParseError('Received data is not a valid '
+                                     'JSONAPI Resource Identifier Object')
 
                 return data
 
             request = parser_context.get('request')
 
             # Check for inconsistencies
-            resource_name = utils.get_resource_name(parser_context)
-            if isinstance(resource_name, six.string_types):
-                doesnt_match = data.get('type') != resource_name
-            else:
-                doesnt_match = data.get('type') not in resource_name
-            if doesnt_match and request.method in ('PUT', 'POST', 'PATCH'):
-                raise exceptions.Conflict(
-                    "The resource object's type ({data_type}) is not the type "
-                    "that constitute the collection represented by the endpoint ({resource_type}).".format(
-                        data_type=data.get('type'),
-                        resource_type=resource_name
-                    )
-                )
+            if request.method in ('PUT', 'POST', 'PATCH'):
+                resource_name = utils.get_resource_name(
+                    parser_context, expand_polymorphic_types=True)
+                if isinstance(resource_name, six.string_types):
+                    if data.get('type') != resource_name:
+                        raise exceptions.Conflict(
+                            "The resource object's type ({data_type}) is not the type that "
+                            "constitute the collection represented by the endpoint "
+                            "({resource_type}).".format(
+                                data_type=data.get('type'),
+                                resource_type=resource_name))
+                else:
+                    if data.get('type') not in resource_name:
+                        raise exceptions.Conflict(
+                            "The resource object's type ({data_type}) is not the type that "
+                            "constitute the collection represented by the endpoint "
+                            "(one of [{resource_types}]).".format(
+                                data_type=data.get('type'),
+                                resource_types=", ".join(resource_name)))
 
             # Construct the return data
             parsed_data = {'id': data.get('id'), 'type': data.get('type')}