### Testen Sie es

Öffnen Sie Ihren Browser unter <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000.</a>

Sie werden folgende JSON-Response sehen:

```JSON
{"message": "Hello World"}
```

### Interaktive API-Dokumentation

Gehen Sie als Nächstes auf <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs </a>.

from pydantic import BaseModel

app = FastAPI()


class JsonApiResponse(JSONResponse):
    media_type = "application/vnd.api+json"


class Error(BaseModel):
    status: str
    title: str


class JsonApiError(BaseModel):
    errors: typing.List[Error]


@app.get(
    "/a",
    status_code=204,
    response_class=JsonApiResponse,

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

你还会需要一个 ASGI 服务器，生产环境可以使用 <a href="https://www.uvicorn.org" class="external-link" target="_blank">Uvicorn</a> 或者 <a href="https://gitlab.com/pgjones/hypercorn" class="external-link" target="_blank">Hypercorn</a>。

<div class="termy">

```console
$ pip install "uvicorn[standard]"

---> 100%
```

</div>

* <a href="https://hub.docker.com/_/postgres" class="external-link" target="_blank">PostgreSQL</a>
* <a href="https://hub.docker.com/_/mysql" class="external-link" target="_blank">MySQL</a>
* <a href="https://hub.docker.com/_/mongo" class="external-link" target="_blank">MongoDB</a>
* <a href="https://hub.docker.com/_/redis" class="external-link" target="_blank">Redis</a>

и т.п.

## Testing locally with Traefik

You can easily run the experiment locally with a stripped path prefix using <a href="https://docs.traefik.io/" class="external-link" target="_blank">Traefik</a>.

<a href="https://github.com/containous/traefik/releases" class="external-link" target="_blank">Download Traefik</a>, it's a single binary, you can extract the compressed file and run it directly from the terminal.

        name="foo",
        field_info=field_info,
        type_=Union[str, List[int]],
        class_validators={},
        model_config=BaseConfig,
    )
    assert not is_pv1_scalar_field(field)


@needs_pydanticv2
def test_get_model_config():
    # For coverage in Pydantic v2
    class Foo(BaseModel):
        model_config = ConfigDict(from_attributes=True)

    foo = Foo()

    alias: Optional[str] = None,
    mode: Literal["validation", "serialization"] = "validation",
) -> ModelField:
    """
    Create a new response field. Raises if type_ is invalid.
    """
    class_validators = class_validators or {}
    if PYDANTIC_V2:
        field_info = field_info or FieldInfo(
            annotation=type_, default=default, alias=alias
        )
    else:
        field_info = field_info or FieldInfo()

```Python hl_lines="6-7"
{!../../../docs_src/path_params/tutorial001.py!}
```

La valeur du paramètre `item_id` sera transmise à la fonction dans l'argument `item_id`.

Именно поэтому, FastAPI сам предоставляет альтернативную документацию API (используя ReDoc), которую можно получить по адресу: <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>.

运行示例并访问 <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>，返回的响应如下：

```JSON
{"item_id":3}
```

!!! check "检查"

    注意，函数接收并返回的值是 `3`（ `int`），不是 `"3"`（`str`）。

    **FastAPI** 通过类型声明自动<abbr title="将来自 HTTP 请求中的字符串转换为 Python 数据类型">**解析**请求中的数据</abbr>。

## 数据校验