prevent endless loop in extensions when augmenting schema #426

drf_spectacular/extensions.py

@@ -53,16 +53,17 @@ def get_name(self) -> Optional[str]:
 
     def map_serializer(self, auto_schema: 'AutoSchema', direction):
         """ override for customized serializer mapping """
-        return auto_schema._map_basic_serializer(self.target_class, direction)
+        return auto_schema._map_serializer(self.target_class, direction, bypass_extensions=True)
 
 
 class OpenApiSerializerFieldExtension(OpenApiGeneratorExtension['OpenApiSerializerFieldExtension']):
     """
     Extension for replacing an insufficient or specifying an unknown SerializerField schema.
 
     To augment the default schema, you can get what `drf-spectacular` would generate with
-    ``auto_schema._map_serializer_field(self.target, direction)``. Beware that this may
-    still emit warnings, in which case manual construction is advisable.
+    ``auto_schema._map_serializer_field(self.target, direction, bypass_extensions=True)``.
+    and edit the returned schema at your discretion. Beware that this may still emit
+    warnings, in which case manual construction is advisable.
 
     ``map_serializer_field()`` is expected to return a valid `OpenAPI schema object
     <https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#schema-object>`_.

drf_spectacular/openapi.py

@@ -448,7 +448,7 @@ def _map_model_field(self, model_field, direction):
             )
             return build_basic_type(OpenApiTypes.STR)
 
-    def _map_serializer_field(self, field, direction):
+    def _map_serializer_field(self, field, direction, bypass_extensions=False):
         meta = self._get_serializer_field_meta(field)
 
         if has_override(field, 'field'):
@@ -476,7 +476,7 @@ def _map_serializer_field(self, field, direction):
                 return append_meta(schema, meta)
 
         serializer_field_extension = OpenApiSerializerFieldExtension.get_match(field)
-        if serializer_field_extension:
+        if serializer_field_extension and not bypass_extensions:
             schema = serializer_field_extension.map_serializer_field(self, direction)
             if serializer_field_extension.get_name():
                 component = ResolvedComponent(
@@ -695,11 +695,11 @@ def _map_min_max(self, field, content):
         if field.min_value:
             content['minimum'] = field.min_value
 
-    def _map_serializer(self, serializer, direction):
+    def _map_serializer(self, serializer, direction, bypass_extensions=False):
         serializer = force_instance(serializer)
         serializer_extension = OpenApiSerializerExtension.get_match(serializer)
 
-        if serializer_extension:
+        if serializer_extension and not bypass_extensions:
             schema = serializer_extension.map_serializer(self, direction)
         else:
             schema = self._map_basic_serializer(serializer, direction)