![Swagger UI](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* Click on the button "Try it out", it allows you to fill the parameters and directly interact with the API:

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-04-swagger-03.png)

!!! note "Примітка"
     Django REST Framework створив Том Крісті. Той самий творець Starlette і Uvicorn, на яких базується **FastAPI**.


!!! check "Надихнуло **FastAPI** на"
     Мати автоматичний веб-інтерфейс документації API.

### <a href="https://flask.palletsprojects.com" class="external-link" target="_blank">Flask</a>

You need to import `WSGIMiddleware`.

Then wrap the WSGI (e.g. Flask) app with the middleware.

And then mount that under a path.

```Python hl_lines="2-3  23"
{!../../../docs_src/wsgi/tutorial001.py!}
```

## Check it

Now, every request under the path `/v1/` will be handled by the Flask application.

And the rest will be handled by **FastAPI**.

We will later use this `engine` in other places.

```Python hl_lines="8-10"
{!../../../docs_src/sql_databases/sql_app/database.py!}
```

#### Note

The argument:

```Python
connect_args={"check_same_thread": False}
```

...is needed only for `SQLite`. It's not needed for other databases.

!!! info "Technical Details"

## 선택적 매개변수

같은 방법으로 기본값을 `None`으로 설정하여 선택적 매개변수를 선언할 수 있습니다:

```Python hl_lines="9"
{!../../../docs_src/query_params/tutorial002.py!}
```

이 경우 함수 매개변수 `q`는 선택적이며 기본값으로 `None` 값이 됩니다.

!!! check "확인"
    **FastAPI**는 `item_id`가 경로 매개변수이고 `q`는 경로 매개변수가 아닌 쿼리 매개변수라는 것을 알 정도로 충분히 똑똑합니다.

!!! note "참고"
    FastAPI는 `q`가 `= None`이므로 선택적이라는 것을 인지합니다.

    ```

=== "Python 3.8+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/query_params/tutorial002.py!}
    ```


本例中，查询参数 `q` 是可选的，默认值为 `None`。

!!! check "检查"

    注意，**FastAPI** 可以识别出 `item_id` 是路径参数，`q` 不是路径参数，而是查询参数。

!!! note "笔记"

    因为默认值为 `= None`，FastAPI 把 `q` 识别为可选参数。

And the part after the `yield` will be executed **after** the application has finished.

### Async Context Manager

If you check, the function is decorated with an `@asynccontextmanager`.

That converts the function into something called an "**async context manager**".

```Python hl_lines="1  13"
{!../../../docs_src/events/tutorial003.py!}
```

```

!!! tip
    ✔️ 🤯 👈 🚥 👆 💚 ⚙️ 🎏 💽, 💖 ✳, 👆 🚫 🚫 🔀 🎻. 👆 🔜 💪 ⚙️ 🎏 🏒 💽 🎓.

#### 🗒

❌:

```Python
check_same_thread=False
```

🌓 1️⃣ 🇸🇲 🔰:

```Python
connect_args={"check_same_thread": False}
```

...⚫️ 💪 🕴 `SQLite`.

!!! info "📡 ℹ"

    ⚫️❔ 🎏 📡 ℹ [🗄 (🔗) 💽](../tutorial/sql-databases.md#_7){.internal-link target=_blank} ✔.

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

---

<div style="text-align: left; direction: ltr;">"If you're looking to learn one <strong>modern framework</strong> for building REST APIs, check out <strong>FastAPI</strong> [...] It's fast, easy to use and easy to learn [...]"</div>