!!! check
    This will give you editor support inside of your function, with error checks, completion, etc.

## Data <abbr title="also known as: serialization, parsing, marshalling">conversion</abbr>

If you run this example and open your browser at <a href="http://127.0.0.1:8000/items/3" class="external-link" target="_blank">http://127.0.0.1:8000/items/3</a>, you will see a response of:

```JSON
{"item_id":3}
```

!!! check

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

Ein **Kontextmanager** in Python ist etwas, das Sie in einer `with`-Anweisung verwenden können, zum Beispiel kann `open()` als Kontextmanager verwendet werden:

```Python
with open("file.txt") as file:
    file.read()
```

In neueren Versionen von Python gibt es auch einen **asynchronen Kontextmanager**. Sie würden ihn mit `async with` verwenden:

```Python

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

Um **gerenciador de contexto** em Python é algo que você pode usar em uma declaração `with`, por exemplo, `open()` pode ser usado como um gerenciador de contexto:

```Python
with open("file.txt") as file:
    file.read()
```

Nas versões mais recentes de Python, há também um **gerenciador de contexto assíncrono**. Você o usaria com `async with`:

```Python

Up to here, everything would work as normally.

But then, when you open the integrated docs UI (the frontend), it would expect to get the OpenAPI schema at `/openapi.json`, instead of `/api/v1/openapi.json`.

That's why when talking about version 2.0 it's common to say "Swagger", and for version 3+ "OpenAPI".

!!! check "Inspired **FastAPI** to"
    Adopt and use an open standard for API specifications, instead of a custom schema.

    And integrate standards-based user interface tools:

```

</div>

And open the docs at <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

You will see the automatic API docs for the main app, including only its own _path operations_:

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

* **Robusto**: Crea codice pronto per la produzione con documentazione automatica interattiva.
* **Basato sugli standard**: Basato su (e completamente compatibile con) gli open standard per le API: <a href="https://github.com/OAI/OpenAPI-Specification" class="external-link" target="_blank">OpenAPI</a> (precedentemente Swagger) e <a href="https://json-schema.org/" class="external-link" target="_blank">JSON Schema</a>.

    그럼에도, **FastAPI**는 표준 Open API를 사용해 이미 호환이 가능합니다.

    따라서 Swagger UI 또는 기타 그 외의 OpenAPI를 지원하는 툴이 다중 파일 업로드를 지원하는 경우, 이들은 **FastAPI**와 호환됩니다.

!!! note "기술적 세부사항"
    `from starlette.responses import HTMLResponse` 역시 사용할  수 있습니다.

🖼, <a href="https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files" class="external-link" target="_blank">👆 💪 ⚙️ `with` ✍ 📁</a>:

```Python
with open("./somefile.txt") as f:
    contents = f.read()
    print(contents)
```

🔘, `open("./somefile.txt")` ✍ 🎚 👈 🤙 "🔑 👨‍💼".

🕐❔ `with` 🍫 🏁, ⚫️ ⚒ 💭 🔐 📁, 🚥 📤 ⚠.

🕐❔ 👆 ✍ 🔗 ⏮️ `yield`, **FastAPI** 🔜 🔘 🗜 ⚫️ 🔑 👨‍💼, &amp; 🌀 ⚫️ ⏮️ 🎏 🔗 🧰.

```hl_lines="4"
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

That line shows the URL where your app is being served, in your local machine.

### Check it

Open your browser at <a href="http://127.0.0.1:8000" class="external-link" target="_blank">http://127.0.0.1:8000</a>.

You will see the JSON response as:

```JSON
{"message": "Hello World"}
```

### Interactive API docs