```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

Die Datei `main.py` hätte als Inhalt:

```Python
{!../../../docs_src/async_tests/main.py!}
```

Die Datei `test_main.py` hätte die Tests für `main.py`, das könnte jetzt so aussehen:

```Python
{!../../../docs_src/async_tests/test_main.py!}
```

## Es ausführen

## The main `FastAPI`

Now, let's see the module at `app/main.py`.

Here's where you import and use the class `FastAPI`.

This will be the main file in your application that ties everything together.

And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI`

```
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

📁 `main.py` 🔜 ✔️:

```Python
{!../../../docs_src/async_tests/main.py!}
```

📁 `test_main.py` 🔜 ✔️ 💯 `main.py`, ⚫️ 💪 👀 💖 👉 🔜:

```Python
{!../../../docs_src/async_tests/test_main.py!}
```

## 🏃 ⚫️

👆 💪 🏃 👆 💯 🐌 📨:

<div class="termy">

```console

В вашем FastAPI приложении, импортируйте и вызовите `uvicorn` напрямую:

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

### Описание `__name__ == "__main__"`

Главная цель использования `__name__ == "__main__"` в том, чтобы код выполнялся при запуске файла с помощью:

<div class="termy">

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

</div>

```Python hl_lines="11  19"
{!../../../docs_src/sub_applications/tutorial001.py!}
```

### Check the automatic API docs

Now, run `uvicorn` with the main app, if your file is `main.py`, it would be:

<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)
```

</div>

Dans votre application FastAPI, importez et exécutez directement `uvicorn` :

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

### À propos de `__name__ == "__main__"`

Le but principal de `__name__ == "__main__"` est d'avoir du code qui est exécuté lorsque votre fichier est appelé avec :

<div class="termy">

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

</div>

## 🤙 `uvicorn`

👆 FastAPI 🈸, 🗄 & 🏃 `uvicorn` 🔗:

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

### 🔃 `__name__ == "__main__"`

👑 🎯 `__name__ == "__main__"` ✔️ 📟 👈 🛠️ 🕐❔ 👆 📁 🤙 ⏮️:

<div class="termy">

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

</div>

✋️ 🚫 🤙 🕐❔ ➕1️⃣ 📁 🗄 ⚫️, 💖:

```Python
from myapp import app
```

因此，为了能够在同一个文件中使用它们，我们直接导入子模块：

```Python hl_lines="5" title="app/main.py"
{!../../../docs_src/bigger_applications/app/main.py!}
```

### 包含 `users` 和 `items` 的 `APIRouter`

现在，让我们来包含来自 `users` 和 `items` 子模块的 `router`。

```Python hl_lines="10-11" title="app/main.py"
{!../../../docs_src/bigger_applications/app/main.py!}
```

!!! info

<span style="color: green;">INFO</span>:     Application startup complete.
```

</div>

!!! note
    `uvicorn main:app` 命令含义如下:

    * `main`：`main.py` 文件（一个 Python「模块」）。
    * `app`：在 `main.py` 文件中通过 `app = FastAPI()` 创建的对象。
    * `--reload`：让服务器在更新代码后重新启动。仅在开发时使用该选项。


在输出中，会有一行信息像下面这样：

```hl_lines="4"

<div class="termy">

```console
// Here we don't set the env var yet
$ python main.py

// As we didn't set the env var, we get the default value

Hello World from Python

// But if we create an environment variable first
$ export MY_NAME="Wade Wilson"

// And then call the program again
$ python main.py

// Now it can read the environment variable

Hello Wade Wilson from Python
```