Merge pull request #723 from mjumbewu/multitable-inheritance

Use parent's primary key when model is derived via multitable inheritance

rest_framework/serializers.py

@@ -456,8 +456,11 @@ class ModelSerializer(Serializer):
                 "Serializer class '%s' is missing 'model' Meta option" % self.__class__.__name__
         opts = get_concrete_model(cls)._meta
         pk_field = opts.pk
-        # while pk_field.rel:
-        #     pk_field = pk_field.rel.to._meta.pk
+
+        # If model is a child via multitable inheritance, use parent's pk
+        while pk_field.rel and pk_field.rel.parent_link:
+            pk_field = pk_field.rel.to._meta.pk
+
         fields = [pk_field]
         fields += [field for field in opts.fields if field.serialize]
         fields += [field for field in opts.many_to_many if field.serialize]

rest_framework/tests/multitable_inheritance.py

+from __future__ import unicode_literals
+from django.db import models
+from django.test import TestCase
+from rest_framework import serializers
+from rest_framework.tests.models import RESTFrameworkModel
+
+
+# Models
+class ParentModel(RESTFrameworkModel):
+    name1 = models.CharField(max_length=100)
+
+
+class ChildModel(ParentModel):
+    name2 = models.CharField(max_length=100)
+
+
+class AssociatedModel(RESTFrameworkModel):
+    ref = models.OneToOneField(ParentModel, primary_key=True)
+    name = models.CharField(max_length=100)
+
+
+# Serializers
+class DerivedModelSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = ChildModel
+
+
+class AssociatedModelSerializer(serializers.ModelSerializer):
+    class Meta:
+        model = AssociatedModel
+
+
+# Tests
+class IneritedModelSerializationTests(TestCase):
+
+    def test_multitable_inherited_model_fields_as_expected(self):
+        """
+        Assert that the parent pointer field is not included in the fields
+        serialized fields
+        """
+        child = ChildModel(name1='parent name', name2='child name')
+        serializer = DerivedModelSerializer(child)
+        self.assertEqual(set(serializer.data.keys()),
+                         set(['name1', 'name2', 'id']))
+
+    def test_onetoone_primary_key_model_fields_as_expected(self):
+        """
+        Assert that a model with a onetoone field that is the primary key is
+        not treated like a derived model
+        """
+        parent = ParentModel(name1='parent name')
+        associate = AssociatedModel(name='hello', ref=parent)
+        serializer = AssociatedModelSerializer(associate)
+        self.assertEqual(set(serializer.data.keys()),
+                         set(['name', 'ref']))
+
+    def test_data_is_valid_without_parent_ptr(self):
+        """
+        Assert that the pointer to the parent table is not a required field
+        for input data
+        """
+        data = {
+            'name1': 'parent name',
+            'name2': 'child name',
+        }
+        serializer = DerivedModelSerializer(data=data)
+        self.assertEqual(serializer.is_valid(), True)