API refactor

venv/lib/python3.12/site-packages/fastapi/encoders.py

@@ -22,9 +22,9 @@ from pydantic import BaseModel
 from pydantic.color import Color
 from pydantic.networks import AnyUrl, NameEmail
 from pydantic.types import SecretBytes, SecretStr
-from typing_extensions import Annotated, Doc  # type: ignore [attr-defined]
+from typing_extensions import Annotated, Doc
 
-from ._compat import PYDANTIC_V2, Url, _model_dump
+from ._compat import PYDANTIC_V2, UndefinedType, Url, _model_dump
 
 
 # Taken from Pydantic v1 as is
@@ -86,7 +86,7 @@ ENCODERS_BY_TYPE: Dict[Type[Any], Callable[[Any], Any]] = {
 
 
 def generate_encoders_by_class_tuples(
-    type_encoder_map: Dict[Any, Callable[[Any], Any]]
+    type_encoder_map: Dict[Any, Callable[[Any], Any]],
 ) -> Dict[Callable[[Any], Any], Tuple[Any, ...]]:
     encoders_by_class_tuples: Dict[Callable[[Any], Any], Tuple[Any, ...]] = defaultdict(
         tuple
@@ -219,7 +219,7 @@ def jsonable_encoder(
         if not PYDANTIC_V2:
             encoders = getattr(obj.__config__, "json_encoders", {})  # type: ignore[attr-defined]
             if custom_encoder:
-                encoders.update(custom_encoder)
+                encoders = {**encoders, **custom_encoder}
         obj_dict = _model_dump(
             obj,
             mode="json",
@@ -241,6 +241,7 @@ def jsonable_encoder(
             sqlalchemy_safe=sqlalchemy_safe,
         )
     if dataclasses.is_dataclass(obj):
+        assert not isinstance(obj, type)
         obj_dict = dataclasses.asdict(obj)
         return jsonable_encoder(
             obj_dict,
@@ -259,6 +260,8 @@ def jsonable_encoder(
         return str(obj)
     if isinstance(obj, (str, int, float, type(None))):
         return obj
+    if isinstance(obj, UndefinedType):
+        return None
     if isinstance(obj, dict):
         encoded_dict = {}
         allowed_keys = set(obj.keys())