## 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

, 🗄 👍 🚫 ⚙️ 👁 `Bucket` 🎚 💗 "<abbr title="A sequence of code being executed by the program, while at the same time, or at intervals, there can be others being executed too.">🧵</abbr>Ⓜ",, 👥 💪 🤚 🥡 🔗 &amp; 🚶‍♀️ ⚫️ 👆 🚙 🔢:

```Python hl_lines="49-53"
{!../../../docs_src/nosql_databases/tutorial001.py!}
```

## 🌃

    * Will have the best performance, as it doesn't have much extra code apart from the server itself.
    * You wouldn't write an application in Uvicorn directly. That would mean that your code would have to include more or less, at least, all the code provided by Starlette (or **FastAPI**). And if you did that, your final application would have the same overhead as having used a framework and minimizing your app code and bugs.

# About FastAPI versions

**FastAPI** is already being used in production in many applications and systems. And the test coverage is kept at 100%. But its development is still moving quickly.

New features are added frequently, bugs are fixed regularly, and the code is still continuously improving.

In this example we'll create a temporary database only for the tests.

## File structure

We create a new file at `sql_app/tests/test_sql_app.py`.

So the new file structure looks like:

``` hl_lines="9-11"
.
└── sql_app
    ├── __init__.py
    ├── crud.py
    ├── database.py
    ├── main.py
    ├── models.py

!!! tip
    If you want to call `async` functions in your tests apart from sending requests to your FastAPI application (e.g. asynchronous database functions), have a look at the [Async Tests](../advanced/async-tests.md){.internal-link target=_blank} in the advanced tutorial.

## Separating tests

In a real application, you probably would have your tests in a different file.

    We are not restricted to having only one dependency that can return that type of data.

## Other models

You can now get the current user directly in the *path operation functions* and deal with the security mechanisms at the **Dependency Injection** level, using `Depends`.

And you can use any model or data for the security requirements (in this case, a Pydantic model `User`).

 <font color="#4E9A06">╭─────────── FastAPI CLI - Production mode ───────────╮</font>
 <font color="#4E9A06">│                                                     │</font>
 <font color="#4E9A06">│  Serving at: http://0.0.0.0:8000                    │</font>
 <font color="#4E9A06">│                                                     │</font>
 <font color="#4E9A06">│  API docs: http://0.0.0.0:8000/docs                 │</font>

* **Swagger UI**: served at `/docs`.
    * You can set its URL with the parameter `docs_url`.
    * You can disable it by setting `docs_url=None`.
* **ReDoc**: served at `/redoc`.
    * You can set its URL with the parameter `redoc_url`.
    * You can disable it by setting `redoc_url=None`.

For example, to set Swagger UI to be served at `/documentation` and disable ReDoc:

```Python hl_lines="3"

```

</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">