### What is a Program

The word **program** is commonly used to describe many things:

* The **code** that you write, the **Python files**.
* The **file** that can be **executed** by the operating system, for example: `python`, `python.exe` or `uvicorn`.

You can set them as follows:

```Python hl_lines="3-16  19-32"
{!../../../docs_src/metadata/tutorial001.py!}
```

!!! tip
    You can write Markdown in the `description` field and it will be rendered in the output.

With this configuration, the automatic API docs would look like:

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

## License identifier

`UploadFile` 支持以下 `async` 方法，（使用内部 `SpooledTemporaryFile`）可调用相应的文件方法。

* `write(data)`：把 `data` （`str` 或 `bytes`）写入文件；
* `read(size)`：按指定数量的字节或字符（`size` (`int`)）读取文件内容；
* `seek(offset)`：移动至文件 `offset` （`int`）字节处的位置；
    * 例如，`await myfile.seek(0) ` 移动到文件开头；

`UploadFile` имеет следующие методы `async`. Все они вызывают соответствующие файловые методы (используя внутренний SpooledTemporaryFile).

* `write(data)`: Записать данные `data` (`str` или `bytes`) в файл.
* `read(size)`: Прочитать количество `size` (`int`) байт/символов из файла.
* `seek(offset)`: Перейти к байту на позиции `offset` (`int`) в файле.

### `Scope`（作用域）

OAuth2 还支持客户端发送**`scope`**表单字段。

虽然表单字段的名称是 `scope`（单数），但实际上，它是以空格分隔的，由多个**scope**组成的长字符串。

**作用域**只是不带空格的字符串。

常用于声明指定安全权限，例如：

* 常见用例为，`users:read` 或 `users:write`
* 脸书和 Instagram 使用 `instagram_basic`
* 谷歌使用 `https://www.googleapis.com/auth/drive`

!!! info "说明"

    OAuth2 中，**作用域**只是声明指定权限的字符串。

    是否使用冒号 `:` 等符号，或是不是 URL 并不重要。

    这些细节只是特定的实现方式。

### `scope`

🔌 💬 👈 👩‍💻 💪 📨 ➕1️⃣ 📨 🏑 "`scope`".

📨 🏑 📛 `scope` (⭐), ✋️ ⚫️ 🤙 📏 🎻 ⏮️ "↔" 🎏 🚀.

🔠 "↔" 🎻 (🍵 🚀).

👫 🛎 ⚙️ 📣 🎯 💂‍♂ ✔, 🖼:

* `users:read` ⚖️ `users:write` ⚠ 🖼.
* `instagram_basic` ⚙️ 👱📔 / 👱📔.
* `https://www.googleapis.com/auth/drive` ⚙️ 🇺🇸🔍.

!!! info
    Oauth2️⃣ "↔" 🎻 👈 📣 🎯 ✔ ✔.

    ⚫️ 🚫 🤔 🚥 ⚫️ ✔️ 🎏 🦹 💖 `:` ⚖️ 🚥 ⚫️ 📛.

    👈 ℹ 🛠️ 🎯.

* the data sent by your program to be received by the client through the network
* the contents of a file in the disk to be read by the system and given to your program
* the contents your program gave to the system to be written to disk
* a remote API operation
* a database operation to finish
* a database query to return the results
* etc.

    By creating functions that are only dedicated to interacting with the database (get a user or an item) independent of your *path operation function*, you can more easily reuse them in multiple parts and also add <abbr title="Automated tests, written in code, that check if another piece of code is working correctly.">unit tests</abbr> for them.

### Create data

Now create utility functions to create data.

The steps are:

---

The main point is, **none** of these are **rules written in stone** that you have to blindly follow. You can use these ideas to **evaluate your own use case** and decide what is the best approach for your system, checking out how to manage the concepts of:

* Security - HTTPS

from typing_extensions import Annotated

app = FastAPI()


def write_log(message: str):
    with open("log.txt", mode="a") as log:
        log.write(message)


def get_query(background_tasks: BackgroundTasks, q: Union[str, None] = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q


@app.post("/send-notification/{email}")