Fixing #6053: injection of read-only default values is done too late

rest_framework/serializers.py

@@ -370,6 +370,12 @@ class Serializer(BaseSerializer):
             field for field in self.fields.values() if not field.read_only
         ]
 
+    @cached_property
+    def _read_only_fields(self):
+        return [
+            field for field in self.fields.values() if field.read_only
+        ]
+
     @cached_property
     def _readable_fields(self):
         return [
@@ -457,14 +463,6 @@ class Serializer(BaseSerializer):
 
         return defaults
 
-    def run_validators(self, value):
-        """
-        Add read_only fields with defaults to value before running validators.
-        """
-        to_validate = self._read_only_defaults()
-        to_validate.update(value)
-        super(Serializer, self).run_validators(to_validate)
-
     def to_internal_value(self, data):
         """
         Dict of native values <- Dict of primitive datatypes.
@@ -479,9 +477,11 @@ class Serializer(BaseSerializer):
 
         ret = OrderedDict()
         errors = OrderedDict()
-        fields = self._writable_fields
+        writable_fields = self._writable_fields
+        read_only_fields = self._read_only_fields
+        read_only_defaults = self._read_only_defaults()
 
-        for field in fields:
+        for field in writable_fields:
             validate_method = getattr(self, 'validate_' + field.field_name, None)
             primitive_value = field.get_value(data)
             try:
@@ -497,6 +497,11 @@ class Serializer(BaseSerializer):
             else:
                 set_value(ret, field.source_attrs, validated_value)
 
+        for field in read_only_fields:
+            primitive_value = field.get_value(read_only_defaults)
+            if primitive_value is not empty:
+                set_value(ret, field.source_attrs, primitive_value)
+
         if errors:
             raise ValidationError(errors)
 

tests/test_serializer.py

@@ -613,3 +613,32 @@ class TestDeclaredFieldInheritance:
         assert len(Parent().get_fields()) == 2
         assert len(Child().get_fields()) == 2
         assert len(Grandchild().get_fields()) == 2
+
+
+class Test5922Regression:
+    class Point(object):
+        def __init__(self, srid, x, y):
+            self.srid = srid
+            self.coords = (x, y)
+
+    def setup(self):
+
+        # Declares a serializer that converts data into an object
+        class NestedPointSerializer(serializers.Serializer):
+            longitude = serializers.FloatField(source='x')
+            latitude = serializers.FloatField(source='y')
+
+            def to_internal_value(self, data):
+                kwargs = super(NestedPointSerializer, self).to_internal_value(data)
+                return Test5922Regression.Point(srid=4326, **kwargs)
+
+        self.Serializer = NestedPointSerializer
+
+    def test_5922_regression(self):
+        serializer = self.Serializer(data={'longitude': 6.958307, 'latitude': 50.941357})
+        assert serializer.is_valid()
+        assert isinstance(serializer.validated_data, Test5922Regression.Point)
+        assert serializer.validated_data.srid == 4326
+        assert serializer.validated_data.coords[0] == 6.958307
+        assert serializer.validated_data.coords[1] == 50.941357
+        assert serializer.errors == {}