Par exemple, en étendant le modèle précédent, vous pouvez vouloir ajouter un paramètre `importance` dans le même body, en plus des paramètres `item` et `user`.

Si vous le déclarez tel quel, comme c'est une valeur [scalaire](https://docs.github.com/fr/graphql/reference/scalars), **FastAPI** supposera qu'il s'agit d'un paramètre de requête (`Query`).

# Reference

Here's the reference or code API, the classes, functions, parameters, attributes, and
all the FastAPI parts you can use in your applications.

If you want to **learn FastAPI** you are much better off reading the

`FastAPI` là một class kế thừa trực tiếp `Starlette`.

Bạn cũng có thể sử dụng tất cả <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> chức năng với `FastAPI`.

///

### Bước 2: Tạo một `FastAPI` "instance"

{* ../../docs_src/first_steps/tutorial001.py hl[3] *}

Biến `app` này là một "instance" của class `FastAPI`.

Đây sẽ là điểm cốt lõi để tạo ra tất cả API của bạn.

```

But FastAPI (actually Starlette) provides a simpler way to do it that makes sure that the internal middlewares handle server errors and custom exception handlers work properly.

For that, you use `app.add_middleware()` (as in the example for CORS).

```Python
from fastapi import FastAPI
from unicorn import UnicornMiddleware

app = FastAPI()

Он интегрирован в FastAPI, так что вы можете импортировать его прямо из `fastapi` и избежать случайного импорта `BackgroundTask` (без `s` на конце) из `starlette.background`.

При использовании `BackgroundTasks` (а не `BackgroundTask`), вам достаточно только определить параметр функции с типом `BackgroundTasks` и **FastAPI** сделает все за вас, также как при использовании объекта `Request`.

/// note | 📡 ℹ

👆 💪 ⚙️ `from starlette.responses import JSONResponse`.

**FastAPI** 🚚 🎏 `starlette.responses` `fastapi.responses` 🏪 👆, 👩‍💻. ✋️ 🌅 💪 📨 👟 🔗 ⚪️➡️ 💃.

///

## 🛬 🛃 `Response`

🖼 🔛 🎦 🌐 🍕 👆 💪, ✋️ ⚫️ 🚫 📶 ⚠, 👆 💪 ✔️ 📨 `item` 🔗, & **FastAPI** 🔜 🚮 ⚫️ `JSONResponse` 👆, 🏭 ⚫️ `dict`, ♒️. 🌐 👈 🔢.

🔜, ➡️ 👀 ❔ 👆 💪 ⚙️ 👈 📨 🛃 📨.

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

### ⚒ `root_path` FastAPI 📱

👐, 🚥 👆 🚫 ✔️ 🌌 🚚 📋 ⏸ 🎛 💖 `--root-path` ⚖️ 🌓, 👆 💪 ⚒ `root_path` 🔢 🕐❔ 🏗 👆 FastAPI 📱:

{* ../../docs_src/behind_a_proxy/tutorial002.py hl[3] *}

🚶‍♀️ `root_path` `FastAPI` 🔜 🌓 🚶‍♀️ `--root-path` 📋 ⏸ 🎛 Uvicorn ⚖️ Hypercorn.

### 🔃 `root_path`

```

/// note | `async` 📡 ℹ

🕐❔ 👆 ⚙️ `async` 👩‍🔬, **FastAPI** 🏃 📁 👩‍🔬 🧵 & ⌛ 👫.

///

/// note | 💃 📡 ℹ

**FastAPI**'Ⓜ `UploadFile` 😖 🔗 ⚪️➡️ **💃**'Ⓜ `UploadFile`, ✋️ 🚮 💪 🍕 ⚒ ⚫️ 🔗 ⏮️ **Pydantic** & 🎏 🍕 FastAPI.

///

## ⚫️❔ "📨 💽"

🌌 🕸 📨 (`<form></form>`) 📨 💽 💽 🛎 ⚙️ "🎁" 🔢 👈 📊, ⚫️ 🎏 ⚪️➡️ 🎻.

**FastAPI** 🔜 ⚒ 💭 ✍ 👈 📊 ⚪️➡️ ▶️️ 🥉 ↩️ 🎻.

/// note | 📡 ℹ

///

## The main `FastAPI` { #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` { #import-fastapi }

{* ../../docs_src/websockets/tutorial001.py hl[2,6:38,41:43] *}

## ✍ `websocket`

👆 **FastAPI** 🈸, ✍ `websocket`:

{* ../../docs_src/websockets/tutorial001.py hl[1,46:47] *}

/// note | 📡 ℹ

👆 💪 ⚙️ `from starlette.websockets import WebSocket`.

**FastAPI** 🚚 🎏 `WebSocket` 🔗 🏪 👆, 👩‍💻. ✋️ ⚫️ 👟 🔗 ⚪️➡️ 💃.

///

## ⌛ 📧 & 📨 📧