From 45b472be8d735d9ad238b46f166efe8a862e594c Mon Sep 17 00:00:00 2001
From: Yurii Motov <yurii.motov.monte@gmail.com>
Date: Wed, 3 Dec 2025 22:52:36 +0100
Subject: [PATCH] Rename `form_max_part_size` to `max_part_size`

---
 fastapi/applications.py                       |  9 +++-----
 fastapi/routing.py                            | 21 ++++++++-----------
 tests/test_form_max_fields_files_part_size.py |  4 ++--
 3 files changed, 14 insertions(+), 20 deletions(-)

diff --git a/fastapi/applications.py b/fastapi/applications.py
index f7f36aff6..da3d4e9f9 100644
--- a/fastapi/applications.py
+++ b/fastapi/applications.py
@@ -2646,14 +2646,11 @@ class FastAPI(Starlette):
                 """
             ),
         ] = 1000,
-        form_max_part_size: Annotated[
+        max_part_size: Annotated[
             int,
             Doc(
                 """
-                Maximum size (in bytes) for each part in a form submission.
-
-                This limits the size of each part in a form submission to prevent
-                potential denial-of-service attacks.
+                Maximum size (in bytes) for each part in a multipart form submission.
                 """
             ),
         ] = 1024 * 1024,
@@ -2704,7 +2701,7 @@ class FastAPI(Starlette):
             generate_unique_id_function=generate_unique_id_function,
             form_max_fields=form_max_fields,
             form_max_files=form_max_files,
-            form_max_part_size=form_max_part_size,
+            max_part_size=max_part_size,
         )
 
     def delete(
diff --git a/fastapi/routing.py b/fastapi/routing.py
index 4e2aeecd1..4e3f65bfd 100644
--- a/fastapi/routing.py
+++ b/fastapi/routing.py
@@ -302,7 +302,7 @@ def get_request_handler(
     embed_body_fields: bool = False,
     form_max_fields: int = 1000,
     form_max_files: int = 1000,
-    form_max_part_size: int = 1024 * 1024,
+    max_part_size: int = 1024 * 1024,
 ) -> Callable[[Request], Coroutine[Any, Any, Response]]:
     assert dependant.call is not None, "dependant.call must be a function"
     is_coroutine = dependant.is_coroutine_callable
@@ -329,7 +329,7 @@ def get_request_handler(
                     body = await request.form(
                         max_fields=form_max_fields,
                         max_files=form_max_files,
-                        max_part_size=form_max_part_size,
+                        max_part_size=max_part_size,
                     )
                     file_stack.push_async_callback(body.close)
                 else:
@@ -544,7 +544,7 @@ class APIRoute(routing.Route):
         ] = Default(generate_unique_id),
         form_max_fields: int = 1000,
         form_max_files: int = 1000,
-        form_max_part_size: int = 1024 * 1024,
+        max_part_size: int = 1024 * 1024,
     ) -> None:
         self.path = path
         self.endpoint = endpoint
@@ -577,7 +577,7 @@ class APIRoute(routing.Route):
         self.path_regex, self.path_format, self.param_convertors = compile_path(path)
         self.form_max_fields = form_max_fields
         self.form_max_files = form_max_files
-        self.form_max_part_size = form_max_part_size
+        self.max_part_size = max_part_size
         if methods is None:
             methods = ["GET"]
         self.methods: Set[str] = {method.upper() for method in methods}
@@ -676,7 +676,7 @@ class APIRoute(routing.Route):
             embed_body_fields=self._embed_body_fields,
             form_max_fields=self.form_max_fields,
             form_max_files=self.form_max_files,
-            form_max_part_size=self.form_max_part_size,
+            max_part_size=self.max_part_size,
         )
 
     def matches(self, scope: Scope) -> Tuple[Match, Scope]:
@@ -1056,7 +1056,7 @@ class APIRouter(routing.Router):
             generate_unique_id_function=current_generate_unique_id,
             form_max_fields=form_max_fields,
             form_max_files=form_max_files,
-            form_max_part_size=form_max_part_size,
+            max_part_size=form_max_part_size,
         )
         self.routes.append(route)
 
@@ -2581,14 +2581,11 @@ class APIRouter(routing.Router):
                 """
             ),
         ] = 1000,
-        form_max_part_size: Annotated[
+        max_part_size: Annotated[
             int,
             Doc(
                 """
-                Maximum size (in bytes) for each part in a form submission.
-
-                This limits the size of each part in a form submission to prevent
-                potential denial-of-service attacks.
+                Maximum size (in bytes) for each part in a multipart form submission.
                 """
             ),
         ] = 1024 * 1024,
@@ -2643,7 +2640,7 @@ class APIRouter(routing.Router):
             generate_unique_id_function=generate_unique_id_function,
             form_max_fields=form_max_fields,
             form_max_files=form_max_files,
-            form_max_part_size=form_max_part_size,
+            form_max_part_size=max_part_size,
         )
 
     def delete(
diff --git a/tests/test_form_max_fields_files_part_size.py b/tests/test_form_max_fields_files_part_size.py
index 4e42263c6..9a5056011 100644
--- a/tests/test_form_max_fields_files_part_size.py
+++ b/tests/test_form_max_fields_files_part_size.py
@@ -6,7 +6,7 @@ from fastapi.testclient import TestClient
 app = FastAPI()
 
 
-@app.post("/", form_max_files=2, form_max_part_size=1024, form_max_fields=2)
+@app.post("/", form_max_files=2, max_part_size=1024, form_max_fields=2)
 async def upload_files(files: List[UploadFile] = File(...)):
     return {"filenames": [file.filename for file in files]}
 
@@ -54,7 +54,7 @@ def test_max_part_size_exceeds_custom_limit():
         "small content\r\n"
         f"--{boundary}\r\n"
         f'Content-Disposition: form-data; name="large"\r\n\r\n'
-        + ("x" * 1024 * 10 + "x")  # 1MB + 1 byte of data
+        + ("x" * 1024 + "x")  # 1KB + 1 byte of data
         + "\r\n"
         f"--{boundary}--\r\n"
     ).encode("utf-8")