<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

### Passo 3: crie uma *rota*

#### Rota

"Rota" aqui se refere à última parte da URL, começando do primeiro `/`.

Então, em uma URL como:

```
https://example.com/items/foo
```

...a rota seria:

```
/items/foo
```

!!! info "Informação"

    But because **FastAPI** is based on the Python standards, including `Annotated`, you can use this trick in your code. 😎

The dependencies will keep working as expected, and the **best part** is that the **type information will be preserved**, which means that your editor will be able to keep providing you with **autocompletion**, **inline errors**, etc. The same for other tools like `mypy`.

* <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a> para as partes web.
* <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> para a parte de dados.

## Instalação

<div class="termy">

```console
$ pip install fastapi

---> 100%
```

</div>

That's what would happen to a third party application that tried to access one of these *path operations* with a token provided by a user, depending on how many permissions the user gave the application.

## About third party integrations

In this example we are using the OAuth2 "password" flow.

```Python
some_var.set("new value")
```

To get a value anywhere inside of the context (e.g. in any part handling the current request) use:

```Python
some_var.get()
```

### Set context variables in the `async` dependency `reset_db_state()`

## In a hurry?

<abbr title="too long; didn't read"><strong>TL;DR:</strong></abbr>

If you are using third party libraries that tell you to call them with `await`, like:

```Python
results = await some_library()
```

Then, declare your *path operation functions* with `async def` like:

```Python hl_lines="2"
@app.get('/')

```console
$ pip install "fastapi[all]"

---> 100%
```

</div>

...eso también incluye `uvicorn` que puedes usar como el servidor que ejecuta tu código.

!!! note "Nota"
    También puedes instalarlo parte por parte.

    Esto es lo que probablemente harías una vez que desees implementar tu aplicación en producción:

    ```
    pip install fastapi
    ```

# Simple OAuth2 with Password and Bearer

Now let's build from the previous chapter and add the missing parts to have a complete security flow.

## Get the `username` and `password`

We are going to use **FastAPI** security utilities to get the `username` and `password`.

OAuth2 specifies that when using the "password flow" (that we are using) the client/user must send a `username` and `password` fields as form data.

!!! tip "Dica"
    As próximas seções **não são necessáriamente "avançadas"**

    E é possível que para seu caso de uso, a solução esteja em uma delas.

## Leia o Tutorial primeiro

Você ainda pode usar a maior parte dos recursos no **FastAPI** com o conhecimento do [Tutorial - Guia de Usuário](../tutorial/index.md){.internal-link target=_blank}.

E as próximas seções assumem que você já leu ele, e que você conhece suas ideias principais.

In this section you will see how.

## The normal process

The normal (default) process, is as follows.

A `FastAPI` application (instance) has an `.openapi()` method that is expected to return the OpenAPI schema.

As part of the application object creation, a *path operation* for `/openapi.json` (or for whatever you set your `openapi_url`) is registered.

It just returns a JSON response with the result of the application's `.openapi()` method.