The simplest FastAPI file could look like this:

{* ../../docs_src/first_steps/tutorial001.py *}

Copy that to a file `main.py`.

Run the live server:

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

```Python hl_lines="6-9"
{!../../docs_src/background_tasks/tutorial001.py!}
```

## Adicionar a tarefa em segundo plano

Dentro de sua _função de operação de caminho_, passe sua função de tarefa para o objeto _tarefas em segundo plano_ com o método `.add_task()`:

```Python hl_lines="14"
{!../../docs_src/background_tasks/tutorial001.py!}
```

`.add_task()` recebe como argumentos:

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Add the background task

Inside of your *path operation function*, pass your task function to the *background tasks* object with the method `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001.py hl[14] *}

`.add_task()` receives as arguments:

Por exemplo, para declarar um outro retorno com o status code `404` e um modelo do Pydantic chamado `Message`, você pode escrever:

```Python hl_lines="18  22"
{!../../docs_src/additional_responses/tutorial001.py!}
```

/// note | "Nota"

Lembre-se que você deve retornar o `JSONResponse` diretamente.

///

/// info | "Informação"

A chave `model` não é parte do OpenAPI.

Let's see the previous example again:

{* ../../docs_src/response_status_code/tutorial001.py hl[6] *}

`201` is the status code for "Created".

But you don't have to memorize what each of these codes mean.

You can use the convenience variables from `fastapi.status`.

{* ../../docs_src/response_status_code/tutorial002.py hl[1,6] *}

```Python hl_lines="1  7-12  19-20"
{!../../docs_src/dataclasses/tutorial001.py!}
```

```Python hl_lines="15 16 17 18 19 20 21 22 23"
{!../../docs_src/schema_extra_example/tutorial001.py!}
```

その追加情報はそのまま出力され、JSON Schemaに追加されます。

## `Field`の追加引数

後述する`Field`、`Path`、`Query`、`Body`などでは、任意の引数を関数に渡すことでJSON Schemaの追加情報を宣言することもできます:

```Python hl_lines="4 10 11 12 13"
{!../../docs_src/schema_extra_example/tutorial002.py!}
```

/// warning | "注意"

これらの追加引数が渡されても、文書化のためのバリデーションは追加されず、注釈だけが追加されることを覚えておいてください。

```Python hl_lines="14"
{!../../docs_src/handling_errors/tutorial002.py!}

```

## 安装自定义异常处理器

添加自定义处理器，要使用 [Starlette 的异常工具](https://www.starlette.io/exceptions/)。

假设要触发的自定义异常叫作 `UnicornException`。

且需要 FastAPI 实现全局处理该异常。

此时，可以用 `@app.exception_handler()` 添加自定义异常控制器：

```Python hl_lines="5-7  13-18  24"
{!../../docs_src/handling_errors/tutorial003.py!}

```

# 📨 🎚

## ⚙️ `Response` 🔢

👆 💪 📣 🔢 🆎 `Response` 👆 *➡ 🛠️ 🔢* (👆 💪 🍪).

& ⤴️ 👆 💪 ⚒ 🎚 👈 *🔀* 📨 🎚.

```Python hl_lines="1  7-8"
{!../../docs_src/response_headers/tutorial002.py!}
```

& ⤴️ 👆 💪 📨 🙆 🎚 👆 💪, 👆 🛎 🔜 ( `dict`, 💽 🏷, ♒️).

& 🚥 👆 📣 `response_model`, ⚫️ 🔜 ⚙️ ⛽ & 🗜 🎚 👆 📨.

                </mxCell>
                <mxCell id="3" value="&lt;font style=&quot;font-size: 24px&quot; face=&quot;Roboto&quot;&gt;Package app&lt;br&gt;app/__init__.py&lt;/font&gt;" style="text;html=1;strokeColor=none;fillColor=none;align=center;verticalAlign=middle;whiteSpace=wrap;rounded=0;strokeWidth=3;fontFamily=Roboto Mono, mono;FType=g;" parent="1" vertex="1">