a.external-link {
  /* For right to left languages */
  direction: ltr;
  display: inline-block;
}

a.external-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0[↪]";
}

a.internal-link::after {
  /* \00A0 is a non-breaking space
        to make the mark be on the same line as the link
    */
  content: "\00A0↪";
}

.shadow {

    padding: 75px 45px 35px;
    position: relative;
    -webkit-box-sizing: border-box;
            box-sizing: border-box;
    line-height: 1.2;
}

[data-termynal]:before {
    content: '';
    position: absolute;
    top: 15px;
    left: 15px;
    display: inline-block;
    width: 15px;
    height: 15px;
    border-radius: 50%;
    /* A little hack to display the window buttons in one pseudo element. */

          {% include ".icons/material/email.svg" %}
        </span> Subscribe to the <strong>FastAPI and friends</strong> newsletter 🎉
      </a>
    </div>
    <div class="item">

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In this case, `item_id` is declared to be an `int`.

!!! 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>

# Body - Fields

The same way you can declare additional validation and metadata in *path operation function* parameters with `Query`, `Path` and `Body`, you can declare validation and metadata inside of Pydantic models using Pydantic's `Field`.

## Import `Field`

First, you have to import it:

=== "Python 3.10+"

    ```Python hl_lines="4"
    {!> ../../../docs_src/body_fields/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

```Python
Base.metadata.create_all(bind=engine)
```

That is normally called in `main.py`, but the line in `main.py` uses the database file `sql_app.db`, and we need to make sure we create `test.db` for the tests.

So we add that line here, with the new file.

```Python hl_lines="16"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

    ```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
    You might remember that request bodies are also declared with Pydantic models.

    ```

    </div>

!!! note
    The command `uvicorn main:app` refers to:

    * `main`: the file `main.py` (the Python "module").
    * `app`: the object created inside of `main.py` with the line `app = FastAPI()`.

    It is equivalent to:

    ```Python
    from main import app
    ```

!!! warning

    },
    "user": {
        "username": "dave",
        "full_name": "Dave Grohl"
    }
}
```

!!! note
    Notice that even though the `item` was declared the same way as before, it is now expected to be inside of the body with a key `item`.


**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives it's specific content and the same for `user`.

# Templates

Você pode usar qualquer template engine com o **FastAPI**.

Uma escolha comum é o Jinja2, o mesmo usado pelo Flask e outras ferramentas.

Existem utilitários para configurá-lo facilmente que você pode usar diretamente em sua aplicação **FastAPI** (fornecidos pelo Starlette).

## Instalação de dependências

Para instalar o `jinja2`, siga o código abaixo:

<div class="termy">

```console
$ pip install jinja2
```