```

Et une `description` :

```Python hl_lines="13"
{!../../../docs_src/query_params_str_validations/tutorial008.py!}
```

## Alias de paramètres

Imaginez que vous vouliez que votre paramètre se nomme `item-query`.

Comme dans la requête :

```
http://127.0.0.1:8000/items/?item-query=foobaritems
```

    pass


@app.post("/invoices/", callbacks=invoices_callback_router.routes)
def create_invoice(invoice: Invoice, callback_url: Union[HttpUrl, None] = None):
    """
    Create an invoice.

    This will (let's imagine) let the API user (some external developer) create an
    invoice.

    And this path operation will:

    * Send the invoice to the client.
    * Collect the money from the client.

But there are specific cases where it's useful to get the `Request` object.

## Use the `Request` object directly

Let's imagine you want to get the client's IP address/host inside of your *path operation function*.

For that you need to access the request directly.

```Python hl_lines="1  7-8"

**Concorrência** e **paralelismo** ambos são relacionados a "diferentes coisas acontecendo mais ou menos ao mesmo tempo".

Mas os detalhes entre *concorrência* e *paralelismo* são bem diferentes.

Para ver essa diferença, imagine a seguinte história sobre hambúrgueres:

### Hambúrgueres concorrentes

Você vai com seu _crush_ :heart_eyes: na lanchonete, fica na fila enquanto o caixa pega os pedidos das pessoas na sua frente.

Jusqu'au moment où c'est (enfin) votre tour. Vous allez au comptoir, récupérez vos burgers 🍔 et revenez à votre table.

Vous et votre crush 😍 mangez les burgers 🍔 et passez un bon moment ✨.

---

Imaginez que vous êtes l'ordinateur / le programme 🤖 dans cette histoire.

```Python hl_lines="2"
{!../../../docs_src/python_types/tutorial001.py!}
```

### Edit it

It's a very simple program.

But now imagine that you were writing it from scratch.

At some point you would have started the definition of the function, you had the parameters ready...

But then you have to call "that method that converts the first letter to upper case".

# Security - First Steps

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

```

E uma `description`:

```Python hl_lines="13"
{!../../../docs_src/query_params_str_validations/tutorial008.py!}
```

## Apelidos (alias) de parâmetros

Imagine que você queira que um parâmetro tenha o nome `item-query`.

Desta maneira:

```
http://127.0.0.1:8000/items/?item-query=foobaritems
```

Mas o nome `item-query` não é um nome de váriavel válido no Python.

    This will take microseconds and will only happen at startup.

    So it won't affect performance. ⚡

### Include an `APIRouter` with a custom `prefix`, `tags`, `responses`, and `dependencies`

Now, let's imagine your organization gave you the `app/internal/admin.py` file.

It contains an `APIRouter` with some admin *path operations* that your organization shares between several projects.

## An app with callbacks

Let's see all this with an example.

Imagine you develop an app that allows creating invoices.

These invoices will have an `id`, `title` (optional), `customer`, and `total`.

The user of your API (an external developer) will create an invoice in your API with a POST request.

Then your API will (let's imagine):

* Send the invoice to some customer of the external developer.
* Collect the money.