Merge fc2648ca00 into 6db05770f6

fastapi/params.py

@@ -570,6 +570,12 @@ class Body(FieldInfo):
         else:
             kwargs["deprecated"] = deprecated
         if PYDANTIC_V2:
+            if serialization_alias in (_Unset, None) and isinstance(alias, str):
+                serialization_alias = alias
+
+            if validation_alias in (_Unset, None):
+                validation_alias = alias
+
             kwargs.update(
                 {
                     "annotation": annotation,

tests/test_openapi_form_alias.py

@@ -0,0 +1,34 @@
+import pytest
+from fastapi import FastAPI, Form
+from fastapi.testclient import TestClient
+from typing_extensions import Annotated
+
+app = FastAPI()
+
+
+@app.post("/old-style", operation_id="old_style")
+def route_with_form(form_param: str = Form(alias="aliased-field")):
+    return {}
+
+
+@app.post("/annotated", operation_id="annotated")
+def route_with_form_annotated(form_param: Annotated[str, Form(alias="aliased-field")]):
+    return {}
+
+
+client = TestClient(app)
+
+
+@pytest.mark.parametrize("path", ["/old-style", "/annotated"])
+def test_get_route(path: str):
+    response = client.post(path, data={"aliased-field": "Hello, World!"})
+    assert response.status_code == 200, response.text
+    assert response.json() == {}
+
+
+@pytest.mark.parametrize("schema_obj", ["Body_annotated", "Body_old_style"])
+def test_form_alias_is_correct(schema_obj: str):
+    response = client.get("/openapi.json")
+    assert response.status_code == 200, response.text
+    form_properties = response.json()["components"]["schemas"][schema_obj]["properties"]
+    assert "aliased-field" in form_properties