🔖 Release version 0.140.5 (#16072)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

docs/en/docs/release-notes.md

@@ -7,6 +7,24 @@ hide:
 
 ## Latest Changes
 
+## 0.140.5 (2026-07-27)
+
+### Refactors
+
+* ⚡️ Avoid flattening dependencies for body fields. PR [#16071](https://github.com/fastapi/fastapi/pull/16071) by [@tiangolo](https://github.com/tiangolo).
+
+## 0.140.4 (2026-07-27)
+
+### Refactors
+
+* ⚡️ Skip unused dependency repeat bookkeeping. PR [#16069](https://github.com/fastapi/fastapi/pull/16069) by [@tiangolo](https://github.com/tiangolo).
+
+## 0.140.3 (2026-07-27)
+
+### Refactors
+
+* ⚡️ Avoid repeated dependency flattening in OpenAPI. PR [#16067](https://github.com/fastapi/fastapi/pull/16067) by [@tiangolo](https://github.com/tiangolo).
+
 ## 0.140.2 (2026-07-27)
 
 ### Refactors

fastapi/__init__.py

@@ -1,6 +1,6 @@
 """FastAPI framework, high performance, easy to learn, fast to code, ready for production"""
 
-__version__ = "0.140.2"
+__version__ = "0.140.5"
 
 from starlette import status as status
 

fastapi/dependencies/utils.py

@@ -152,16 +152,20 @@ def get_flat_dependant(
     parent_oauth_scopes: list[str] | None = None,
     _uses_scopes_cache: _UsesScopesCache | None = None,
 ) -> Dependant:
-    if visited is None:
-        visited = []
-    if _uses_scopes_cache is None:
-        _uses_scopes_cache = {}
-    visited.append(
-        _get_cache_key(
-            dependant=dependant,
-            uses_scopes_cache=_uses_scopes_cache,
-        )
+    track_visited = (
+        skip_repeats or visited is not None or _uses_scopes_cache is not None
     )
+    if track_visited:
+        if visited is None:
+            visited = []
+        if _uses_scopes_cache is None:
+            _uses_scopes_cache = {}
+        visited.append(
+            _get_cache_key(
+                dependant=dependant,
+                uses_scopes_cache=_uses_scopes_cache,
+            )
+        )
     use_parent_oauth_scopes = (parent_oauth_scopes or []) + (
         _get_oauth_scopes(dependant=dependant)
     )
@@ -187,15 +191,16 @@ def get_flat_dependant(
         scope=dependant.scope,
     )
     for sub_dependant in dependant.dependencies:
-        if (
-            skip_repeats
-            and _get_cache_key(
-                dependant=sub_dependant,
-                uses_scopes_cache=_uses_scopes_cache,
-            )
-            in visited
-        ):
-            continue
+        if skip_repeats:
+            assert visited is not None
+            if (
+                _get_cache_key(
+                    dependant=sub_dependant,
+                    uses_scopes_cache=_uses_scopes_cache,
+                )
+                in visited
+            ):
+                continue
         flat_sub = get_flat_dependant(
             sub_dependant,
             skip_repeats=skip_repeats,
@@ -214,6 +219,16 @@ def get_flat_dependant(
     return flat_dependant
 
 
+def _get_flat_body_params(dependant: Dependant) -> list[ModelField]:
+    body_params: list[ModelField] = []
+    dependants = [dependant]
+    while dependants:
+        current_dependant = dependants.pop()
+        body_params.extend(current_dependant.body_params)
+        dependants.extend(reversed(current_dependant.dependencies))
+    return body_params
+
+
 def _get_flat_fields_from_params(fields: list[ModelField]) -> list[ModelField]:
     if not fields:
         return fields
@@ -1038,8 +1053,8 @@ async def request_body_to_args(
     return values, errors
 
 
-def get_body_field(
-    *, flat_dependant: Dependant, name: str, embed_body_fields: bool
+def _get_body_field(
+    *, body_params: list[ModelField], name: str, embed_body_fields: bool
 ) -> ModelField | None:
     """
     Get a ModelField representing the request body for a path operation, combining
@@ -1051,34 +1066,30 @@ def get_body_field(
     This is **not** used to validate/parse the request body, that's done with each
     individual body parameter.
     """
-    if not flat_dependant.body_params:
+    if not body_params:
         return None
-    first_param = flat_dependant.body_params[0]
+    first_param = body_params[0]
     if not embed_body_fields:
         return first_param
     model_name = "Body_" + name
-    BodyModel = create_body_model(
-        fields=flat_dependant.body_params, model_name=model_name
-    )
-    required = any(
-        True for f in flat_dependant.body_params if f.field_info.is_required()
-    )
+    BodyModel = create_body_model(fields=body_params, model_name=model_name)
+    required = any(True for f in body_params if f.field_info.is_required())
     BodyFieldInfo_kwargs: dict[str, Any] = {
         "annotation": BodyModel,
         "alias": "body",
     }
     if not required:
         BodyFieldInfo_kwargs["default"] = None
-    if any(isinstance(f.field_info, params.File) for f in flat_dependant.body_params):
+    if any(isinstance(f.field_info, params.File) for f in body_params):
         BodyFieldInfo: type[params.Body] = params.File
-    elif any(isinstance(f.field_info, params.Form) for f in flat_dependant.body_params):
+    elif any(isinstance(f.field_info, params.Form) for f in body_params):
         BodyFieldInfo = params.Form
     else:
         BodyFieldInfo = params.Body
 
         body_param_media_types = [
             f.field_info.media_type
-            for f in flat_dependant.body_params
+            for f in body_params
             if isinstance(f.field_info, params.Body)
         ]
         if len(set(body_param_media_types)) == 1:

fastapi/openapi/utils.py

@@ -112,7 +112,7 @@ def get_openapi_security_definitions(
 
 def _get_openapi_operation_parameters(
     *,
-    dependant: Dependant,
+    flat_dependant: Dependant,
     model_name_map: ModelNameMap,
     field_mapping: dict[
         tuple[ModelField, Literal["validation", "serialization"]], dict[str, Any]
@@ -120,7 +120,6 @@ def _get_openapi_operation_parameters(
     separate_input_output_schemas: bool = True,
 ) -> list[dict[str, Any]]:
     parameters = []
-    flat_dependant = get_flat_dependant(dependant, skip_repeats=True)
     path_params = _get_flat_fields_from_params(flat_dependant.path_params)
     query_params = _get_flat_fields_from_params(flat_dependant.query_params)
     header_params = _get_flat_fields_from_params(flat_dependant.header_params)
@@ -284,12 +283,22 @@ def get_openapi_path(
     assert current_response_class, "A response class is needed to generate OpenAPI"
     route_response_media_type: str | None = current_response_class.media_type
     if route.include_in_schema:
+        flat_dependant = get_flat_dependant(route.dependant, skip_repeats=True)
+        all_route_params = [
+            field
+            for fields in (
+                flat_dependant.path_params,
+                flat_dependant.query_params,
+                flat_dependant.header_params,
+                flat_dependant.cookie_params,
+            )
+            for field in _get_flat_fields_from_params(fields)
+        ]
         for method in route.methods:
             operation = get_openapi_operation_metadata(
                 route=route, method=method, operation_ids=operation_ids
             )
             parameters: list[dict[str, Any]] = []
-            flat_dependant = get_flat_dependant(route.dependant, skip_repeats=True)
             security_definitions, operation_security = get_openapi_security_definitions(
                 flat_dependant=flat_dependant
             )
@@ -298,7 +307,7 @@ def get_openapi_path(
             if security_definitions:
                 security_schemes.update(security_definitions)
             operation_parameters = _get_openapi_operation_parameters(
-                dependant=route.dependant,
+                flat_dependant=flat_dependant,
                 model_name_map=model_name_map,
                 field_mapping=field_mapping,
                 separate_input_output_schemas=separate_input_output_schemas,
@@ -458,7 +467,6 @@ def get_openapi_path(
                     deep_dict_update(openapi_response, process_response)
                     openapi_response["description"] = description
             http422 = "422"
-            all_route_params = get_flat_params(route.dependant)
             if (all_route_params or route.body_field) and not any(
                 status in operation["responses"]
                 for status in [http422, "4XX", "default"]

fastapi/routing.py

@@ -55,10 +55,10 @@ from fastapi.dependencies.models import (
     _is_gen_callable,
 )
 from fastapi.dependencies.utils import (
+    _get_body_field,
+    _get_flat_body_params,
     _should_embed_body_fields,
-    get_body_field,
     get_dependant,
-    get_flat_dependant,
     get_parameterless_sub_dependant,
     get_stream_item_type,
     get_typed_return_annotation,
@@ -849,16 +849,16 @@ def _build_dependant_with_parameterless_dependencies(
     path: str,
     call: Callable[..., Any],
     dependencies: Sequence[params.Depends],
-) -> tuple[Dependant, Dependant, bool]:
+) -> tuple[Dependant, list[ModelField], bool]:
     dependant = get_dependant(path=path, call=call, scope="function")
     for depends in dependencies[::-1]:
         dependant.dependencies.insert(
             0,
             get_parameterless_sub_dependant(depends=depends, path=path),
         )
-    flat_dependant = get_flat_dependant(dependant)
-    embed_body_fields = _should_embed_body_fields(flat_dependant.body_params)
-    return dependant, flat_dependant, embed_body_fields
+    body_params = _get_flat_body_params(dependant)
+    embed_body_fields = _should_embed_body_fields(body_params)
+    return dependant, body_params, embed_body_fields
 
 
 class _RouteWithPath(Protocol):
@@ -1090,15 +1090,15 @@ def _populate_api_route_state(
     assert callable(endpoint), "An endpoint must be a callable"
     (
         route.dependant,
-        flat_dependant,
+        body_params,
         route._embed_body_fields,
     ) = _build_dependant_with_parameterless_dependencies(
         path=route.path_format,
         call=route.endpoint,
         dependencies=route.dependencies,
     )
-    route.body_field = get_body_field(
-        flat_dependant=flat_dependant,
+    route.body_field = _get_body_field(
+        body_params=body_params,
         name=route.unique_id,
         embed_body_fields=route._embed_body_fields,
     )