Add PrimaryKeyWriteSerializerReadField.

Author: gibsonbailey

ckc/fields.py

@@ -0,0 +1,19 @@
+from rest_framework import serializers
+
+
+class PrimaryKeyWriteSerializerReadField(serializers.PrimaryKeyRelatedField):
+    def __init__(self, *args, **kwargs):
+        read_serializer = kwargs.pop('read_serializer', None)
+        assert read_serializer is not None, (
+            'PrimaryKeyWriteSerializerReadField must provide `read_serializer` argument.'
+        )
+        super().__init__(*args, **kwargs)
+        self.read_serializer = read_serializer
+
+    # Related fields will not look up any of the object's values for normal primary
+    # key serialization. This override forces the lookup of the entire object.
+    def use_pk_only_optimization(self):
+        return False
+
+    def to_representation(self, value):
+        return self.read_serializer(value, context=self.context).data

testproject/testapp/misconfigured_serializers.py

@@ -0,0 +1,17 @@
+from rest_framework.serializers import ModelSerializer
+
+from ckc.fields import PrimaryKeyWriteSerializerReadField
+from testapp.models import AModel, BModel
+
+
+class MisconfiguredSerializer(ModelSerializer):
+    a = PrimaryKeyWriteSerializerReadField(
+        queryset=AModel.objects.all(),  # This field requires a read_serializer kwarg
+    )
+
+    class Meta:
+        model = BModel
+        fields = (
+            'id',
+            'a'
+        )

testproject/testapp/models.py

@@ -12,6 +12,10 @@ class AModel(SoftDeletableModel):
     title = models.CharField(max_length=255, default="I'm a test!")
 
 
+class BModel(models.Model):
+    a = models.ForeignKey(AModel, on_delete=models.CASCADE)
+
+
 class ModelWithACreator(models.Model):
     created_by = models.ForeignKey(User, on_delete=models.CASCADE)
 

testproject/testapp/serializers.py

@@ -1,7 +1,8 @@
 from rest_framework.serializers import ModelSerializer
 
+from ckc.fields import PrimaryKeyWriteSerializerReadField
 from ckc.serializers import DefaultUserCreateMixin
-from testapp.models import ModelWithACreator, ModelWithADifferentNamedCreator
+from testapp.models import ModelWithACreator, ModelWithADifferentNamedCreator, AModel, BModel
 
 
 class TestModelWithACreatorSerializer(DefaultUserCreateMixin, ModelSerializer):
@@ -15,3 +16,26 @@ class Meta:
         model = ModelWithADifferentNamedCreator
         fields = []
         user_field = 'owner'
+
+
+class AModelSerializer(ModelSerializer):
+    class Meta:
+        model = AModel
+        fields = (
+            'id',
+            'title',
+        )
+
+
+class BModelSerializer(ModelSerializer):
+    a = PrimaryKeyWriteSerializerReadField(
+        queryset=AModel.objects.all(),
+        read_serializer=AModelSerializer,
+    )
+
+    class Meta:
+        model = BModel
+        fields = (
+            'id',
+            'a'
+        )

testproject/testapp/viewsets.py

@@ -1,7 +1,8 @@
 from rest_framework.viewsets import ModelViewSet
 
-from testapp.models import ModelWithACreator, ModelWithADifferentNamedCreator
-from testapp.serializers import TestModelWithACreatorSerializer, TestModelWithADifferentNamedCreatorSerializer
+from testapp.models import ModelWithACreator, ModelWithADifferentNamedCreator, BModel
+from testapp.serializers import TestModelWithACreatorSerializer, TestModelWithADifferentNamedCreatorSerializer, \
+    BModelSerializer
 
 
 class TestModelWithACreatorViewSet(ModelViewSet):
@@ -12,3 +13,8 @@ class TestModelWithACreatorViewSet(ModelViewSet):
 class TestModelWithADifferentNamedCreatorViewSet(ModelViewSet):
     queryset = ModelWithADifferentNamedCreator.objects.all()
     serializer_class = TestModelWithADifferentNamedCreatorSerializer
+
+
+class BModelViewSet(ModelViewSet):
+    queryset = BModel.objects.all()
+    serializer_class = BModelSerializer

testproject/urls.py

@@ -1,10 +1,10 @@
 from rest_framework import routers
 
-from testapp.viewsets import TestModelWithACreatorViewSet, TestModelWithADifferentNamedCreatorViewSet
-
+from testapp.viewsets import TestModelWithACreatorViewSet, TestModelWithADifferentNamedCreatorViewSet, BModelViewSet
 
 router = routers.SimpleRouter()
 router.register(r'creators', TestModelWithACreatorViewSet)
 router.register(r'creators-alternative', TestModelWithADifferentNamedCreatorViewSet)
+router.register(r'bmodel', BModelViewSet)
 
 urlpatterns = router.urls

tests/integration/test_primary_key_write_serializer_read_field.py

@@ -0,0 +1,42 @@
+from django.contrib.auth import get_user_model
+from django.urls import reverse
+from rest_framework.test import APITestCase
+
+from testapp.models import AModel, BModel
+
+User = get_user_model()
+
+
+class TestDefaultUserCreateMixin(APITestCase):
+    TEST_TITLE_1 = 'test_title_1'
+    TEST_TITLE_2 = 'test_title_2'
+
+    def setUp(self):
+        self.user = User.objects.create_user(username="test", password="test")
+        self.client.force_authenticate(self.user)
+        self.a_1 = AModel.objects.create(title=self.TEST_TITLE_1)
+        self.a_2 = AModel.objects.create(title=self.TEST_TITLE_2)
+        self.b = BModel.objects.create(a=self.a_1)
+
+    def test_retrieve_renders_full_serializer_on_field(self):
+        resp = self.client.get(reverse('bmodel-detail', args=(self.b.pk,)))
+        assert resp.status_code == 200
+        assert resp.json()['a']['title'] == self.TEST_TITLE_1
+
+    def test_update_accepts_pk_on_field(self):
+        resp = self.client.patch(
+            reverse('bmodel-detail', args=(self.b.pk,)),
+            {
+                'a': self.a_2.pk,
+            }
+        )
+        assert resp.status_code == 200
+        assert resp.json()['a']['title'] == self.TEST_TITLE_2
+
+    def test_field_fails_if_no_read_serializer_kwarg_passed(self):
+        try:
+            from testapp.misconfigured_serializers import MisconfiguredSerializer  # noqa
+        except AssertionError:
+            pass
+        else:
+            assert False, 'MisconfiguredSerializer should have raised AssertionError'