!!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001.py!}
    ```

!!! warning
    Notice that `Field` is imported directly from `pydantic`, not from `fastapi` as are all the rest (`Query`, `Path`, `Body`, etc).

## Declare model attributes

You can then use `Field` with model attributes:

=== "Python 3.10+"

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

!!! check
    Notice that the value your function received (and returned) is `3`, as a Python `int`, not a string `"3"`.

### Try Out the Client Code

Now you can import and use the client code, it could look like this, notice that you get autocompletion for the methods:

<img src="/img/tutorial/generate-clients/image02.png">

You will also get autocompletion for the payload to send:

<img src="/img/tutorial/generate-clients/image03.png">

!!! tip

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

!!! tip
    Notice that even though you are accessing it at `http://127.0.0.1:8000/app` it shows the `root_path` of `/api/v1`, taken from the option `--root-path`.

```
docs/en/docs/features.md
```

* Paste it in exactly the same location but for the language you want to translate, e.g.:

```
docs/es/docs/features.md
```

!!! tip
    Notice that the only change in the path and file name is the language code, from `en` to `es`.

If you go to your browser you will see that now the docs show your new section (the info box at the top is gone). 🎉

```Python hl_lines="2  12  15-18"
{!../../../docs_src/app_testing/tutorial001.py!}
```

!!! tip
    Notice that the testing functions are normal `def`, not `async def`.

    And the calls to the client are also normal calls, not using `await`.

    This allows you to use `pytest` directly without complications.

!!! note "Technical Details"
    You could also use `from starlette.testclient import TestClient`.

    {!> ../../../docs_src/response_model/tutorial001_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="17  22  24-27"
    {!> ../../../docs_src/response_model/tutorial001.py!}
    ```

!!! note
    Notice that `response_model` is a parameter of the "decorator" method (`get`, `post`, etc). Not of your *path operation function*, like all the parameters and body.

=== "Python 3.8+ non-Annotated"

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="31"
    {!> ../../../docs_src/security/tutorial002.py!}
    ```

Notice that we declare the type of `current_user` as the Pydantic model `User`.

This will help us inside of the function with all the completion and type checks.

!!! tip

* **Facile**: Progettato per essere facile da usare e imparare. Si riduce il tempo da dedicare alla lettura della documentazione.
* **Sintentico**: Minimizza la duplicazione di codice. Molteplici funzionalità, ognuna con la propria dichiarazione dei parametri. Meno errori.
* **Robusto**: Crea codice pronto per la produzione con documentazione automatica interattiva.