Fix for PrimaryKeyRelatedField serializer bug

adrf/serializers.py

@@ -15,6 +15,15 @@
 from rest_framework.utils.serializer_helpers import ReturnDict, ReturnList
 
 
+# NOTE This is the list of fields defined by DRF for which we need to call to_rapresentation.
+DRF_FIELDS = list(DRFModelSerializer.serializer_field_mapping.values()) + [
+    DRFModelSerializer.serializer_related_field,
+    DRFModelSerializer.serializer_related_to_field,
+    DRFModelSerializer.serializer_url_field,
+    DRFModelSerializer.serializer_choice_field,
+]
+
+
 class BaseSerializer(DRFBaseSerializer):
     """
     Base serializer class.
@@ -148,17 +157,13 @@ async def ato_representation(self, instance):
             except SkipField:
                 continue
 
-            is_drf_field = type(field) in list(
-                DRFModelSerializer.serializer_field_mapping.values()
-            ) + [DRFModelSerializer.serializer_choice_field]
-
             check_for_none = (
                 attribute.pk if isinstance(attribute, models.Model) else attribute
             )
             if check_for_none is None:
                 ret[field.field_name] = None
             else:
-                if is_drf_field:
+                if type(field) in DRF_FIELDS:
                     repr = field.to_representation(attribute)
                 else:
                     repr = await field.ato_representation(attribute)

tests/conftest.py

@@ -41,6 +41,7 @@ def pytest_configure(config):
             "django.contrib.staticfiles",
             "rest_framework",
             "rest_framework.authtoken",
+            "tests",
         ),
         PASSWORD_HASHERS=("django.contrib.auth.hashers.MD5PasswordHasher",),
     )

tests/test_models.py

@@ -0,0 +1,7 @@
+from django.db import models
+from django.contrib.auth.models import User
+
+
+class Order(models.Model):
+    name = models.TextField()
+    user = models.ForeignKey(User, on_delete=models.CASCADE)

tests/test_serializers.py

@@ -1,12 +1,12 @@
 from collections import ChainMap
 
 from asgiref.sync import sync_to_async
-from django.contrib.auth.models import User
 from django.test import TestCase
 
 from adrf.serializers import ModelSerializer, Serializer
 from rest_framework import serializers
 from rest_framework.test import APIRequestFactory
+from .test_models import User, Order
 
 factory = APIRequestFactory()
 
@@ -20,7 +20,6 @@ def __init__(self, **kwargs):
             setattr(self, key, val)
 
 
-# replace with django test case
 class TestSerializer(TestCase):
     def setUp(self):
         class SimpleSerializer(Serializer):
@@ -39,14 +38,8 @@ async def acreate(self, validated_data):
             async def aupdate(self, instance, validated_data):
                 return MockObject(**validated_data)
 
-        class MyModelSerializer(ModelSerializer):
-            class Meta:
-                model = User
-                fields = ("username",)
-
         self.simple_serializer = SimpleSerializer
         self.crud_serializer = CrudSerializer
-        self.model_serializer = MyModelSerializer
 
         self.default_data = {
             "username": "test",
@@ -66,15 +59,6 @@ async def test_serializer_valid(self):
         assert await serializer.adata == data
         assert serializer.errors == {}
 
-    async def test_modelserializer_valid(self):
-        data = {
-            "username": "test",
-        }
-        serializer = self.model_serializer(data=data)
-        assert await sync_to_async(serializer.is_valid)()
-        assert await serializer.adata == data
-        assert serializer.errors == {}
-
     async def test_serializer_invalid(self):
         data = {
             "username": "test",
@@ -236,3 +220,36 @@ def test_sync_serializer_valid(self):
         assert serializer.is_valid()
         assert serializer.data == data
         assert serializer.errors == {}
+
+
+class TestModelSerializer(TestCase):
+    def setUp(self) -> None:
+        class UserSerializer(ModelSerializer):
+            class Meta:
+                model = User
+                fields = ("username",)
+
+        class OrderSerializer(ModelSerializer):
+            class Meta:
+                model = Order
+                fields = ("id", "user", "name")
+
+        self.user_serializer = UserSerializer
+        self.order_serializer = OrderSerializer
+
+    async def test_user_serializer_valid(self):
+        data = {
+            "username": "test",
+        }
+        serializer = self.user_serializer(data=data)
+        assert await sync_to_async(serializer.is_valid)()
+        assert await serializer.adata == data
+        assert serializer.errors == {}
+
+    async def test_order_serializer_valid(self):
+        user = await User.objects.acreate(username="test")
+        data = {"user": user.id, "name": "Test order"}
+        serializer = self.order_serializer(data=data)
+        assert await sync_to_async(serializer.is_valid)()
+        assert await serializer.adata == data
+        assert serializer.errors == {}