fix: parameter models with alias

fastapi/dependencies/utils.py

@@ -772,7 +772,7 @@ def request_params_to_args(
                 )
         value = _get_multidict_value(field, received_params, alias=alias)
         if value is not None:
-            params_to_process[field.name] = value
+            params_to_process[field.alias] = value
         processed_keys.add(alias or field.alias)
         processed_keys.add(field.name)
 

tests/test_param_models.py

@@ -0,0 +1,71 @@
+from fastapi import FastAPI
+from fastapi.params import Body, Cookie, Form, Header, Query
+from fastapi.testclient import TestClient
+from pydantic import BaseModel, Field
+from typing_extensions import Annotated
+
+app = FastAPI()
+
+
+class DataModel(BaseModel):
+    alias_with: str = Field(alias="with", default="nothing")
+
+
+@app.post("/param/body")
+def post_param_body(data: Annotated[DataModel, Body()]):
+    return data
+
+
+@app.post("/param/form")
+def post_param_form(data: Annotated[DataModel, Form()]):
+    return data
+
+
+@app.post("/param/query")
+def post_param_query(data: Annotated[DataModel, Query()]):
+    return data
+
+
+@app.post("/param/cookies")
+def post_param_cookies(data: Annotated[DataModel, Cookie()]):
+    return data
+
+
+@app.post("/param/headers")
+def post_param_headers(data: Annotated[DataModel, Header()]):
+    return data
+
+
+client = TestClient(app)
+
+
+def test_param_body_with_alias():
+    response = client.post("/param/body", json={"with": "something"})
+    assert response.status_code == 200, response.text
+    assert response.json() == {"with": "something"}
+
+
+def test_param_form_with_alias():
+    response = client.post("/param/form", data={"with": "something"})
+    assert response.status_code == 200, response.text
+    assert response.json() == {"with": "something"}
+
+
+def test_param_query_with_alias():
+    response = client.post("/param/query", params={"with": "something"})
+    assert response.status_code == 200, response.text
+    assert response.json() == {"with": "something"}
+
+
+def test_param_headers_with_alias():
+    response = client.post("/param/headers", headers={"with": "something"})
+    assert response.status_code == 200, response.text
+    assert response.json() == {"with": "something"}
+
+
+def test_param_cookies_with_alias():
+    with client as c:
+        c.cookies.set("with", "something")
+        response = c.post("/param/cookies")
+    assert response.status_code == 200, response.text
+    assert response.json() == {"with": "something"}