Fix validation for ListSerializer when many=True

rest_framework/serializers.py

@@ -652,6 +652,26 @@ def run_child_validation(self, data):
         self.child.initial_data = data
         return super().run_child_validation(data)
         """
+        child_instance = getattr(self.child, "instance", None)
+
+        if self.instance is not None:
+            pk_name = None
+            child_meta = getattr(self.child, "Meta", None)
+            model = getattr(child_meta, "model", None) if child_meta else None
+
+            if model is not None:
+                pk_name = model._meta.pk.name
+
+            if pk_name:
+                obj_id = data.get(pk_name, data.get("pk", data.get("id")))
+                if obj_id is not None:
+                    for obj in self.instance:
+                        if hasattr(obj, pk_name) and getattr(obj, pk_name) == obj_id:
+                            child_instance = obj
+                            break
+
+        self.child.instance = child_instance
+        self.child.initial_data = data
         return self.child.run_validation(data)
 
     def to_internal_value(self, data):

tests/models.py

@@ -150,3 +150,21 @@ def __new__(cls, *args, **kwargs):
                                    help_text='OneToOneTarget',
                                    verbose_name='OneToOneTarget',
                                    on_delete=models.CASCADE)
+
+
+class ListModelForTest(RESTFrameworkModel):
+    name = models.CharField(max_length=100)
+    status = models.CharField(max_length=100, blank=True)
+
+    @property
+    def is_valid(self):
+        return self.name == 'valid'
+
+
+class EmailPKModel(RESTFrameworkModel):
+    email = models.EmailField(primary_key=True)
+    name = models.CharField(max_length=100)
+
+    @property
+    def is_valid(self):
+        return self.name == 'valid'

tests/test_serializer_lists.py

@@ -5,7 +5,8 @@
 from rest_framework import serializers
 from rest_framework.exceptions import ErrorDetail
 from tests.models import (
-    CustomManagerModel, NullableOneToOneSource, OneToOneTarget
+    CustomManagerModel, EmailPKModel, ListModelForTest, NullableOneToOneSource,
+    OneToOneTarget
 )
 
 
@@ -775,3 +776,67 @@ def test(self):
         queryset = NullableOneToOneSource.objects.all()
         serializer = self.serializer(queryset, many=True)
         assert serializer.data
+
+
+@pytest.mark.django_db
+class TestManyTrueValidationCheck:
+    """
+    Tests ListSerializer validation with many=True across different primary key types
+    (integer and email).
+    """
+
+    def setup_method(self):
+        self.obj1 = ListModelForTest.objects.create(name="valid", status="new")
+        self.obj2 = ListModelForTest.objects.create(name="invalid", status="")
+        self.email_obj1 = EmailPKModel.objects.create(email="test@test.com", name="A")
+        self.email_obj2 = EmailPKModel.objects.create(email="test2@test.com", name="B")
+
+        self.serializer, self.email_serializer = self.get_serializers()
+
+    def get_serializers(self):
+        class ListModelForTestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = ListModelForTest
+                fields = ("id", "name", "status")
+
+            def validate_status(self, value):
+                if value and not self.instance.is_valid:
+                    return False
+                return value
+
+        class EmailPKSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = EmailPKModel
+                fields = ("email", "name")
+                read_only_fields = ('email',)
+
+            def validate_name(self, value):
+                if value and not self.instance.is_valid:
+                    return False
+                return value
+
+        return ListModelForTestSerializer, EmailPKSerializer
+
+    def test_run_child_validation_with_many_true(self):
+        input_data = [
+            {"id": self.obj1.pk, "name": "other", "status": "new"},
+            {"id": self.obj2.pk, "name": "valid", "status": "progress"},
+        ]
+
+        serializer = self.serializer([self.obj1, self.obj2], data=input_data, many=True)
+        assert serializer.is_valid(), serializer.errors
+
+        serializer = self.serializer(ListModelForTest.objects.all(), data=input_data, many=True)
+        assert serializer.is_valid(), serializer.errors
+
+    def test_validation_error_for_invalid_data(self):
+        input_data = [{"id": self.obj1.pk, "name": "", "status": "mystatus"}]
+
+        serializer = self.serializer([self.obj1], data=input_data, many=True)
+        assert not serializer.is_valid()
+        assert "name" in serializer.errors[0]
+
+    def test_email_pk_instance_validation(self):
+        input_data = [{"email": "test@test.com", "name": "bar"}]
+        serializer = self.email_serializer(instance=EmailPKModel.objects.all(), data=input_data, many=True)
+        assert serializer.is_valid(), serializer.errors