Details about the `async def` syntax for *path operation functions* and some background about asynchronous code, concurrency, and parallelism.

## In a hurry? { #in-a-hurry }

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

If you are using third party libraries that tell you to call them with `await`, like:

```Python
results = await some_library()
```

بعداً در مورد میان‌افزارهای دیگر در [راهنمای کاربر پیشرفته: میان‌افزار پیشرفته](../advanced/middleware.md){.internal-link target=_blank} بیشتر بخوانید.

شما در بخش بعدی در مورد این که چگونه با استفاده از یک میان‌افزار، <abbr title="Cross-Origin Resource Sharing">CORS</abbr> را مدیریت کنید، خواهید خواند....

<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)
```

</div>

Abre tu navegador en <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

Verás una página simple como:

<img src="/img/tutorial/websockets/image01.png">

All the same process that applied for path parameters also applies for query parameters:

* Editor support (obviously)
* Data <abbr title="converting the string that comes from an HTTP request into Python data">"parsing"</abbr>
* Data validation
* Automatic documentation

## Defaults { #defaults }

As query parameters are not a fixed part of a path, they can be optional and can have default values.

4️⃣. `Author` 🎻 ⚙️ `response_model` 🔢.

5️⃣. 👆 💪 ⚙️ 🎏 🐩 🆎 ✍ ⏮️ 🎻 📨 💪.

    👉 💼, ⚫️ 📇 `Item` 🎻.

6️⃣. 📥 👥 🛬 📖 👈 🔌 `items` ❔ 📇 🎻.

    FastAPI 🎯 <abbr title="converting the data to a format that can be transmitted">✍</abbr> 💽 🎻.

7️⃣. 📥 `response_model` ⚙️ 🆎 ✍ 📇 `Author` 🎻.

    🔄, 👆 💪 🌀 `dataclasses` ⏮️ 🐩 🆎 ✍.

8️⃣. 👀 👈 👉 *➡ 🛠️ 🔢* ⚙️ 🥔 `def` ↩️ `async def`.

```

</div>

Y abre la documentación en <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

Verás la documentación automática de la API para la aplicación principal, incluyendo solo sus propias _path operations_:

<img src="/img/tutorial/sub-applications/image01.png">

stockage.

Il a été créé pour générer le HTML en backend, pas pour créer des API consommées par un frontend moderne (comme React, Vue.js et Angular) ou par d'autres systèmes (comme les appareils <abbr title="Internet of Things">IoT</abbr>) communiquant avec lui.

### <a href="https://www.django-rest-framework.org/" class="external-link" target="_blank">Django REST Framework</a>

## Vous êtes pressés ?

<abbr title="'too long; didn't read' en anglais, ou 'trop long ; j'ai pas lu'"><strong>TL;DR :</strong></abbr>

Si vous utilisez des bibliothèques tierces qui nécessitent d'être appelées avec `await`, telles que :

```Python
results = await some_library()
```

/// tip | Порада

Щоб дізнатися більше про кожен код статусу і призначення кожного з них, перегляньте документацію <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">MDN</abbr> про HTTP коди статусу</a>.

///

## Легкий спосіб запам'ятати назви

Розглянемо ще раз попередній приклад:

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

Mais tarde, você pode ler mais sobre outros middlewares no [Guia do usuário avançado: Middleware avançado](../advanced/middleware.md){.internal-link target=_blank}.