Sync fastapi docs from 50fa3f7c on 2026-01-11

docs_src/additional_responses/tutorial001_py39.py

@@ -0,0 +1,22 @@
+from fastapi import FastAPI
+from fastapi.responses import JSONResponse
+from pydantic import BaseModel
+
+
+class Item(BaseModel):
+    id: str
+    value: str
+
+
+class Message(BaseModel):
+    message: str
+
+
+app = FastAPI()
+
+
+@app.get("/items/{item_id}", response_model=Item, responses={404: {"model": Message}})
+async def read_item(item_id: str):
+    if item_id == "foo":
+        return {"id": "foo", "value": "there goes my hero"}
+    return JSONResponse(status_code=404, content={"message": "Item not found"})