Aleksei Kotenko <******@****.***> 1712026131 +0100

```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
async with lifespan(app):
    await do_stuff()
```

!!! 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

    path = tmp_path / "test.txt"
    path.write_bytes(b"<file content>")
    path2 = tmp_path / "test2.txt"
    path2.write_bytes(b"<file content2>")

    client = TestClient(app)
    with path.open("rb") as file, path2.open("rb") as file2:
        response = client.post(
            "/files/",
            files=(
                ("files", ("test.txt", file)),
                ("files", ("test2.txt", file2)),
            ),

```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:

    patha = tmp_path / "test.txt"
    pathb = tmp_path / "testb.txt"
    patha.write_text("<file content>")
    pathb.write_text("<file b content>")

    client = TestClient(app)
    with patha.open("rb") as filea, pathb.open("rb") as fileb:
        response = client.post(
            "/files/",
            data={"token": "foo"},
            files={"file": filea, "fileb": ("testb.txt", fileb, "text/plain")},
        )

```

</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>.