from fastapi import APIRouter, FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

router = APIRouter()


@router.get("/users/{id}")
def read_user(segment: str, id: str):
    return {"segment": segment, "id": id}


app.include_router(router, prefix="/{segment}")


client = TestClient(app)


def test_get():
    response = client.get("/seg/users/foo")

    sub_router = APIRouter(lifespan=subrouter_lifespan)

    router = APIRouter(lifespan=router_lifespan)
    router.include_router(sub_router)

    app = FastAPI(lifespan=lifespan)
    app.include_router(router)

    @app.get("/")
    def main(request: Request) -> dict[str, str]:
        assert request.state.app
        assert request.state.router
        assert request.state.sub_router

from fastapi import APIRouter, FastAPI
from fastapi.testclient import TestClient

router = APIRouter()

sub_router = APIRouter()

app = FastAPI()


@sub_router.get("/")
def read_item():
    return {"id": "foo"}


router.include_router(sub_router, prefix="/items")

app.include_router(router)

client = TestClient(app)


def test_path_operation():
    response = client.get("/items/")

from fastapi import APIRouter

router = APIRouter()


@router.post("/")
async def update_admin():

* path operation: operação de rota
* path operation function: função de operação de rota
* prefix: prefixo
* request (as in HTTP request): request (do not change if it's already translated to requisição)
* router (as in FastAPI's router): router (do not change if it's already translated to "roteador" or "roteadores")
* response (as in HTTP response): response (do not change if it's already translated to resposta)
* shutdown (of the app): encerramento

            return

        wrapper = self.receive_wrapper(receive)
        await self.app(scope, wrapper, send)


@router.post("/middleware")
def run_middleware(file: UploadFile = File(..., description="Big File")):
    return {"message": "OK"}


app.include_router(router)
app.add_middleware(ContentSizeLimitMiddleware, max_content_size=2**8)


client = TestClient(app)

from fastapi import APIRouter

router = APIRouter()


@router.post("/")
async def update_admin():

from fastapi import APIRouter, Body

router = APIRouter()


@router.post("/compute/")
def compute(a: int = Body(), b: str = Body()):

///

### Add the callback router { #add-the-callback-router }

At this point you have the *callback path operation(s)* needed (the one(s) that the *external developer*  should implement in the *external API*) in the callback router you created above.

Now use the parameter `callbacks` in *your API's path operation decorator* to pass the attribute `.routes` (that's actually just a `list` of routes/*path operations*) from that callback router:

   *
   * Each call is made on either a reused [Connection] from a pool, or on a new connection
   * established from a planned [Route]. OkHttp won't retry if it's already attempted all
   * available routes.
   *
   * @param retry true if OkHttp will make another attempt
   */
  open fun retryDecision(
    call: Call,
    exception: IOException,
    retry: Boolean,
  ) {