from fastapi import FastAPI
from fastapi.responses import PlainTextResponse

app = FastAPI()


@app.get("/", response_class=PlainTextResponse)
async def main():

from fastapi.responses import PlainTextResponse
from fastapi.testclient import TestClient

from docs_src.advanced_middleware.tutorial003_py39 import app


@app.get("/large")
async def large():
    return PlainTextResponse("x" * 4000, status_code=200)


client = TestClient(app)


def test_middleware():
    response = client.get("/large", headers={"accept-encoding": "gzip"})
    assert response.status_code == 200, response.text

You can import them directly from `fastapi.responses`:

```python
from fastapi.responses import (
    FileResponse,
    HTMLResponse,
    JSONResponse,
    ORJSONResponse,
    PlainTextResponse,
    RedirectResponse,
    Response,
    StreamingResponse,
    UJSONResponse,
)
```

## FastAPI Responses

@app.get("/")
def get_root():
    return {"msg": "Hello World"}


@app.get("/override", response_class=PlainTextResponse)
def get_path_override():
    return "Hello World"


@router_a.get("/")
def get_a():
    return {"msg": "Hello A"}


@router_a.get("/override", response_class=PlainTextResponse)
def get_a_path_override():
    return "Hello A"


@router_a_a.get("/")
def get_a_a():

from fastapi.exceptions import RequestValidationError
from fastapi.responses import PlainTextResponse
from starlette.exceptions import HTTPException as StarletteHTTPException

app = FastAPI()


@app.exception_handler(StarletteHTTPException)
async def http_exception_handler(request, exc):
    return PlainTextResponse(str(exc.detail), status_code=exc.status_code)


@app.exception_handler(RequestValidationError)

@app.get("/")
def get_root():
    return {"msg": "Hello World"}


@app.get("/override", response_class=PlainTextResponse)
def get_path_override():
    return "Hello World"


@router_a.get("/")
def get_a():
    return {"msg": "Hello A"}


@router_a.get("/override", response_class=PlainTextResponse)
def get_a_path_override():
    return "Hello A"


@router_a_a.get("/")
def get_a_a():

from starlette.responses import HTMLResponse as HTMLResponse  # noqa
from starlette.responses import JSONResponse as JSONResponse  # noqa
from starlette.responses import PlainTextResponse as PlainTextResponse  # noqa
from starlette.responses import RedirectResponse as RedirectResponse  # noqa
from starlette.responses import Response as Response  # noqa

{* ../../docs_src/response_directly/tutorial002.py hl[1,18] *}

### `HTMLResponse`

如上文所述，接受文本或字节并返回 HTML 响应。

### `PlainTextResponse`

接受文本或字节并返回纯文本响应。

{* ../../docs_src/custom_response/tutorial005.py hl[2,7,9] *}

### `JSONResponse`

接受数据并返回一个 `application/json` 编码的响应。

如上文所述，这是 **FastAPI** 中使用的默认响应。

{* ../../docs_src/handling_errors/tutorial004_py39.py hl[3:4,9:11,25] *}

/// note | Technical Details

You could also use `from starlette.responses import PlainTextResponse`.

**FastAPI** provides the same `starlette.responses` as `fastapi.responses` just as a convenience for you, the developer. But most of the available responses come directly from Starlette.

///

/// warning

同理，也可以覆盖 `HTTPException` 处理器。

例如，只为错误返回纯文本响应，而不是返回 JSON 格式的内容：

{* ../../docs_src/handling_errors/tutorial004.py hl[3:4,9:11,22] *}

/// note | 技术细节

还可以使用 `from starlette.responses import PlainTextResponse`。

**FastAPI** 提供了与 `starlette.responses` 相同的 `fastapi.responses` 作为快捷方式，但大部分响应都可以直接从 Starlette 导入。

///

### 使用 `RequestValidationError` 的请求体

`RequestValidationError` 包含其接收到的无效数据请求的 `body` 。