Add route-level middleware decorator with tests and docs example

docs_src/route_middleware/tutorial001.py

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+import pytest
+from fastapi.testclient import TestClient
+from fastapi import FastAPI, Request
+from fastapi.route_middleware import route_middleware, verify_jwt, log_route
+
+app = FastAPI()
+
+@app.post("/secure")
+@route_middleware(verify_jwt, log_route)
+async def secure_route(req: Request, is_true: bool):
+    
+    return {"status": "ok", "is_true": is_true,"user":req.user}
+
+@app.post("/open")
+async def open_route(is_true: bool):
+    return {"status": "open", "is_true": is_true}

fastapi/route_middleware.py

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+from functools import wraps
+from fastapi import Request
+from typing import Callable
+
+def route_middleware(*middlewares:Callable):
+    def decorator(route_func:Callable):
+        @wraps(route_func)
+        async def wrapper(*args, **kwargs):
+            req = kwargs.get("req")
+            if req is None:
+                raise ValueError("Route must have 'request: Request' parameter")
+
+            for middleware in middlewares:
+                result = middleware(req)
+                if callable(getattr(result, "__await__", None)):
+                    await result
+
+            return await route_func(*args, **kwargs)
+
+        return wrapper
+    return decorator
+
+
+
+# Example middlewares
+async def verify_jwt(req: Request):
+    # just a mock
+    if not (req.query_params.get("is_true") == "true"):
+        req.user={"name":"xyz","admin":True}
+        from fastapi import HTTPException, status
+        raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Invalid JWT")
+
+def log_route(req: Request):
+    print(f"[LOG] Path: {req.url.path}")

tests/test_route_middleware.py

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+import pytest
+from fastapi.testclient import TestClient
+from fastapi import FastAPI, Request
+from fastapi.route_middleware import route_middleware, verify_jwt, log_route
+
+app = FastAPI()
+
+@app.post("/secure")
+@route_middleware(verify_jwt, log_route)
+async def secure_route(req: Request, is_true: bool):
+    return {"status": "ok", "is_true": is_true,"user":req.user}
+
+@app.post("/open")
+async def open_route(is_true: bool):
+    return {"status": "open", "is_true": is_true}
+
+client = TestClient(app)
+
+def test_secure_route_pass():
+    response = client.post("/secure?is_true=true")
+    assert response.status_code == 200
+
+def test_secure_route_fail():
+    response = client.post("/secure?is_true=false")
+    assert response.status_code == 403
+
+def test_open_route():
+    response = client.post("/open?is_true=false")
+    assert response.status_code == 200