在发送响应之前，只会执行 `yield` 语句及之前的代码：

```Python hl_lines="2-4"
{!../../docs_src/dependencies/tutorial007.py!}
```

生成的值会注入到 *路由函数* 和其他依赖项中：

```Python hl_lines="4"
{!../../docs_src/dependencies/tutorial007.py!}
```

`yield` 语句后面的代码会在创建响应后，发送响应前执行：

```Python hl_lines="5-6"
{!../../docs_src/dependencies/tutorial007.py!}
```

/// tip | 提示

你可以使用 `async` 或普通函数。

**FastAPI** 会像处理普通依赖一样，对每个依赖做正确的处理。

```Python hl_lines="1  15"
{!../../docs_src/debugging/tutorial001.py!}
```

### `__name__ == "__main__"` 에 대하여

`__name__ == "__main__"`의 주요 목적은 다음과 같이 파일이 호출될 때 실행되는 일부 코드를 갖는 것입니다.

<div class="termy">

```console
$ python myapp.py
```

</div>

그러나 다음과 같이 다른 파일을 가져올 때는 호출되지 않습니다.

```Python
from myapp import app
```

#### 추가 세부사항

파일 이름이 `myapp.py`라고 가정해 보겠습니다.

다음과 같이 실행하면

{*../../docs_src/websockets/tutorial001.py hl[48:52]*}

Você pode receber e enviar dados binários, de texto e JSON.

## Tente você mesmo

Se seu arquivo for nomeado `main.py`, execute sua aplicação com:

<div class="termy">

```console
$ fastapi dev main.py

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)

///

## 📁 📊

👫 🖼, ➡️ 💬 👆 ✔️ 📁 📛 `my_super_project` 👈 🔌 🎧-📁 🤙 `sql_app` ⏮️ 📊 💖 👉:

```
.
└── sql_app
    ├── __init__.py
    ├── crud.py
    ├── database.py
    ├── main.py
    ├── models.py
    └── schemas.py
```

📁 `__init__.py` 🛁 📁, ✋️ ⚫️ 💬 🐍 👈 `sql_app` ⏮️ 🌐 🚮 🕹 (🐍 📁) 📦.

🔜 ➡️ 👀 ⚫️❔ 🔠 📁/🕹 🔨.

## ❎ `SQLAlchemy`

🥇 👆 💪 ❎ `SQLAlchemy`:

```Python hl_lines="9  17"
{!> ../../docs_src/request_files/tutorial001_02_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="9  17"
{!> ../../docs_src/request_files/tutorial001_02_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="10  18"
{!> ../../docs_src/request_files/tutorial001_02_an.py!}
```

////

//// tab | Python 3.10+ nicht annotiert

{!> ../../docs_src/request_files/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1"
{!> ../../docs_src/request_files/tutorial001_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip | Dica

Utilize a versão com `Annotated` se possível.

///

```Python hl_lines="1"
{!> ../../docs_src/request_files/tutorial001.py!}
```

////

{!> ../../docs_src/request_forms/tutorial001_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="1"
{!> ../../docs_src/request_forms/tutorial001_an.py!}
```

////

//// tab | Python 3.8+ non-Annotated

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="1"
{!> ../../docs_src/request_forms/tutorial001.py!}
```

////

# Code below omitted 👇
```

<details>
<summary>👀 Visualização completa do arquivo</summary>

```Python
{!> ../../docs_src/separate_openapi_schemas/tutorial001_py310.py!}
```

</details>

////

//// tab | Python 3.9+

```Python hl_lines="9"
{!> ../../docs_src/separate_openapi_schemas/tutorial001_py39.py[ln:1-9]!}

# Code below omitted 👇
```

Это должен быть `list` состоящий из `Depends()`:

//// tab | Python 3.9+

```Python hl_lines="19"
{!> ../../docs_src/dependencies/tutorial006_an_py39.py!}
```

////

//// tab | Python 3.8+

```Python hl_lines="18"
{!> ../../docs_src/dependencies/tutorial006_an.py!}
```

////

//// tab | Python 3.8 без Annotated

/// подсказка

Рекомендуется использовать версию с Annotated, если возможно.

///

# 第一步

最简单的 FastAPI 文件可能像下面这样：

```Python
{!../../docs_src/first_steps/tutorial001.py!}
```

将其复制到 `main.py` 文件中。

运行实时服务器：

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
<span style="color: green;">INFO</span>:     Started reloader process [28720]