def test_router():
    client = TestClient(app)
    with client.websocket_connect("/router") as websocket:
        data = websocket.receive_text()
        assert data == "Hello, router!"


def test_prefix_router():
    client = TestClient(app)
    with client.websocket_connect("/prefix/") as websocket:
        data = websocket.receive_text()
        assert data == "Hello, router with prefix!"


def test_native_prefix_router():

)
router_b_override.include_router(router_b_a, prefix="/a")
router_a.include_router(router_a_a, prefix="/a")
router_a.include_router(
    router_a_b_override, prefix="/b", default_response_class=PlainTextResponse
)
app.include_router(router_a, prefix="/a")
app.include_router(
    router_b_override, prefix="/b", default_response_class=PlainTextResponse
)


client = TestClient(app)

We are importing the submodule `items` directly, instead of importing just its variable `router`.

This is because we also have another variable named `router` in the submodule `users`.

If we had imported one after the other, like:

```Python
from .routers.items import router
from .routers.users import router
```

@router.get("/router-depends/")
async def router_depends(commons: dict = Depends(common_parameters)):
    return {"in": "router-depends", "params": commons}


@router.get("/router-decorator-depends/", dependencies=[Depends(common_parameters)])
async def router_decorator_depends():
    return {"in": "router-decorator-depends"}


app.include_router(router)

client = TestClient(app)

    for method_name in method_names:
        router_method = getattr(APIRouter, method_name)
        app_method = getattr(FastAPI, method_name)
        router_sig = inspect.signature(router_method)
        app_sig = inspect.signature(app_method)
        param: inspect.Parameter
        for key, param in base_sig.parameters.items():
            router_param: inspect.Parameter = router_sig.parameters[key]

These **"type hints"** or annotations are a special syntax that allow declaring the <abbr title="for example: str, int, float, bool">type</abbr> of a variable.

By declaring types for your variables, editors and tools can give you better support.

This is just a **quick tutorial / refresher** about Python type hints. It covers only the minimum necessary to use them with **FastAPI**... which is actually very little.

from fastapi import APIRouter

router = APIRouter()


@router.get("/users/", tags=["users"])
async def read_users():
    return [{"username": "Rick"}, {"username": "Morty"}]


@router.get("/users/me", tags=["users"])
async def read_user_me():
    return {"username": "fakecurrentuser"}


@router.get("/users/{username}", tags=["users"])
async def read_user(username: str):

}

.user .title {
  text-align: center;
}

.user .count {
  font-size: 80%;
  text-align: center;
}

a.announce-link:link,
a.announce-link:visited {
  color: #fff;
}

a.announce-link:hover {
  color: var(--md-accent-fg-color);
}

.announce-wrapper {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  align-items: center;
}

.announce-wrapper div.item {

### 避免名称冲突

我们将直接导入 `items` 子模块，而不是仅导入其 `router` 变量。

这是因为我们在 `users` 子模块中也有另一个名为 `router` 的变量。

如果我们一个接一个地导入，例如：

```Python
from .routers.items import router
from .routers.users import router
```

来自 `users` 的 `router` 将覆盖来自 `items` 中的 `router`，我们将无法同时使用它们。

因此，为了能够在同一个文件中使用它们，我们直接导入子模块：

```Python hl_lines="5" title="app/main.py"

class InvoiceEventReceived(BaseModel):
    ok: bool


invoices_callback_router = APIRouter()


@invoices_callback_router.post(
    "{$callback_url}/invoices/{$request.body.id}", response_model=InvoiceEventReceived
)
def invoice_notification(body: InvoiceEvent):
    pass


@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Union[HttpUrl, None] = None):