This is the case for most of the web applications.

Many, many users, but your server is waiting 🕙 for their not-so-good connection to send their requests.

And then waiting 🕙 again for the responses to come back.

This "waiting" 🕙 is measured in microseconds, but still, summing it all, it's a lot of waiting in the end.

That's why it makes a lot of sense to use asynchronous ⏸🔀⏯ code for web APIs.

- Improved how the API server responds to **list** requests where the response format negotiates to Protobuf. List responses in Protobuf are marshalled one element at the time, drastically reducing memory needed to serve large collections. Streaming list responses can be disabled via the `StreamingCollectionEncodingToProtobuf` feature gate. ([#129407](https://github.com/kubernetes/kubernetes/pull/129407),...

/// note | Detalles Técnicos

También podrías usar `from starlette.responses import HTMLResponse`.

**FastAPI** proporciona las mismas `starlette.responses` como `fastapi.responses` solo como una conveniencia para ti, el desarrollador. Pero la mayoría de los responses disponibles vienen directamente de Starlette.

///

client = TestClient(app)


def test_main():
    response = client.get("/app")
    assert response.status_code == 200
    assert response.json() == {"message": "Hello World", "root_path": "/api/v1"}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200
    assert response.json() == snapshot(
        {
            "openapi": "3.1.0",

from fastapi import FastAPI
from fastapi.responses import ORJSONResponse

app = FastAPI()


@app.get("/items/", response_class=ORJSONResponse)
async def read_items():

def test_path_operation(client: TestClient):
    response = client.get("/items/foo")
    assert response.status_code == 200, response.text
    assert response.json() == {"id": "foo", "value": "there goes my hero"}


@workdir_lock
def test_path_operation_img(client: TestClient):
    shutil.copy("./docs/en/docs/img/favicon.png", "./image.png")
    response = client.get("/items/foo?img=1")
    assert response.status_code == 200, response.text

```JSON
{"message": "Oops! yolo did something. There goes a rainbow..."}
```

/// note | 技術詳細

また、`from starlette.requests import Request`と`from starlette.responses import JSONResponse`を使用することもできます。

**FastAPI** は開発者の利便性を考慮して、`fastapi.responses`と同じ`starlette.responses`を提供しています。しかし、利用可能なレスポンスのほとんどはStarletteから直接提供されます。これは`Request`と同じです。

///

## デフォルトの例外ハンドラのオーバーライド { #override-the-default-exception-handlers }

from fastapi import FastAPI
from fastapi.responses import RedirectResponse

app = FastAPI()


@app.get("/pydantic", response_class=RedirectResponse, status_code=302)
async def redirect_pydantic():

client = TestClient(app)


def test_get_api_route():
    response = client.get("/")
    assert response.status_code == 200, response.text
    assert response.json() == {"c": {}, "d": {"a": {}}}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == snapshot(
        {
            "openapi": "3.1.0",

from fastapi import FastAPI
from fastapi.responses import RedirectResponse

app = FastAPI()


@app.get("/teleport")
async def get_teleport() -> RedirectResponse: