🐛 Recurse into dataclass when encoding

fastapi/encoders.py

@@ -1,6 +1,7 @@
 import dataclasses
 from collections import defaultdict
 from enum import Enum
+from functools import partial
 from pathlib import PurePath
 from types import GeneratorType
 from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Union
@@ -41,6 +42,15 @@ def jsonable_encoder(
         include = set(include)
     if exclude is not None and not isinstance(exclude, (set, dict)):
         exclude = set(exclude)
+    _recurse = partial(
+        jsonable_encoder,
+        by_alias=by_alias,
+        exclude_unset=exclude_unset,
+        exclude_defaults=exclude_defaults,
+        exclude_none=exclude_none,
+        custom_encoder=custom_encoder,
+        sqlalchemy_safe=sqlalchemy_safe,
+    )
     if isinstance(obj, BaseModel):
         encoder = getattr(obj.__config__, "json_encoders", {})
         if custom_encoder:
@@ -55,15 +65,10 @@ def jsonable_encoder(
         )
         if "__root__" in obj_dict:
             obj_dict = obj_dict["__root__"]
-        return jsonable_encoder(
-            obj_dict,
-            exclude_none=exclude_none,
-            exclude_defaults=exclude_defaults,
-            custom_encoder=encoder,
-            sqlalchemy_safe=sqlalchemy_safe,
-        )
+        return _recurse(obj_dict, custom_encoder=encoder)
     if dataclasses.is_dataclass(obj):
-        return dataclasses.asdict(obj)
+        obj_dict = dataclasses.asdict(obj)
+        return _recurse(obj_dict)
     if isinstance(obj, Enum):
         return obj.value
     if isinstance(obj, PurePath):
@@ -82,38 +87,18 @@ def jsonable_encoder(
                 and (value is not None or not exclude_none)
                 and ((include and key in include) or not exclude or key not in exclude)
             ):
-                encoded_key = jsonable_encoder(
-                    key,
-                    by_alias=by_alias,
-                    exclude_unset=exclude_unset,
-                    exclude_none=exclude_none,
-                    custom_encoder=custom_encoder,
-                    sqlalchemy_safe=sqlalchemy_safe,
-                )
-                encoded_value = jsonable_encoder(
-                    value,
-                    by_alias=by_alias,
-                    exclude_unset=exclude_unset,
-                    exclude_none=exclude_none,
-                    custom_encoder=custom_encoder,
-                    sqlalchemy_safe=sqlalchemy_safe,
-                )
+                encoded_key = _recurse(key)
+                encoded_value = _recurse(value)
                 encoded_dict[encoded_key] = encoded_value
         return encoded_dict
     if isinstance(obj, (list, set, frozenset, GeneratorType, tuple)):
         encoded_list = []
         for item in obj:
             encoded_list.append(
-                jsonable_encoder(
+                _recurse(
                     item,
                     include=include,
                     exclude=exclude,
-                    by_alias=by_alias,
-                    exclude_unset=exclude_unset,
-                    exclude_defaults=exclude_defaults,
-                    exclude_none=exclude_none,
-                    custom_encoder=custom_encoder,
-                    sqlalchemy_safe=sqlalchemy_safe,
                 )
             )
         return encoded_list
@@ -142,12 +127,4 @@ def jsonable_encoder(
         except Exception as e:
             errors.append(e)
             raise ValueError(errors)
-    return jsonable_encoder(
-        data,
-        by_alias=by_alias,
-        exclude_unset=exclude_unset,
-        exclude_defaults=exclude_defaults,
-        exclude_none=exclude_none,
-        custom_encoder=custom_encoder,
-        sqlalchemy_safe=sqlalchemy_safe,
-    )
+    return _recurse(data)

tests/test_serialize_response_dataclass.py

@@ -1,8 +1,9 @@
+from dataclasses import dataclass
+from datetime import date
 from typing import List, Optional
 
 from fastapi import FastAPI
 from fastapi.testclient import TestClient
-from pydantic.dataclasses import dataclass
 
 app = FastAPI()
 
@@ -14,6 +15,11 @@ class Item:
     owner_ids: Optional[List[int]] = None
 
 
+@dataclass
+class EncodingItem:
+    date: date
+
+
 @app.get("/items/valid", response_model=Item)
 def get_valid():
     return {"name": "valid", "price": 1.0}
@@ -29,6 +35,11 @@ def get_coerce():
     return {"name": "coerce", "price": "1.0"}
 
 
+@app.get("/items/encoding", response_model=EncodingItem)
+def get_encoding():
+    return {"date": date(2022, 1, 20)}
+
+
 @app.get("/items/validlist", response_model=List[Item])
 def get_validlist():
     return [
@@ -82,6 +93,12 @@ def test_coerce():
     assert response.json() == {"name": "coerce", "price": 1.0, "owner_ids": None}
 
 
+def test_encoding():
+    response = client.get("/items/encoding")
+    response.raise_for_status()
+    assert response.json() == {"date": "2022-01-20"}
+
+
 def test_validlist():
     response = client.get("/items/validlist")
     response.raise_for_status()