It is used by many companies including Mozilla, Red Hat and Eventbrite.

It was one of the first examples of **automatic API documentation**, and this was specifically one of the first ideas that inspired "the search for" **FastAPI**.

!!! note

    username: username string. The OAuth2 spec requires the exact field name "username".
    password: password string. The OAuth2 spec requires the exact field name "password".
    scope: Optional string. Several scopes (each one a string) separated by spaces. E.g.
        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)

                be `None`.

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be
                provided in one of multiple optional ways (for example, in HTTP Basic
                authentication or in an HTTP Bearer token).
                """
            ),
        ] = True,
    ):

This can be used as a quick shortcut if you have only one Pydantic model and want to remove some data from the output.

!!! tip
    But it is still recommended to use the ideas above, using multiple classes, instead of these parameters.

#### Operation

"Operation" here refers to one of the HTTP "methods".

One of:

* `POST`
* `GET`
* `PUT`
* `DELETE`

...and the more exotic ones:

* `OPTIONS`
* `HEAD`
* `PATCH`
* `TRACE`

In the HTTP protocol, you can communicate to each path using one (or more) of these "methods".

---

# Generate Clients

As **FastAPI** is based on the OpenAPI specification, you get automatic compatibility with many tools, including the automatic API docs (provided by Swagger UI).

One particular advantage that is not necessarily obvious is that you can **generate clients** (sometimes called <abbr title="Software Development Kits">**SDKs**</abbr> ) for your API, for many different **programming languages**.

## OpenAPI Client Generators

## About proxies with a stripped path prefix

Keep in mind that a proxy with stripped path prefix is only one of the ways to configure it.

Probably in many cases the default will be that the proxy doesn't have a stripped path prefix.

次の章では、FastAPIアプリケーションをデプロイするための**具体的なレシピ**を紹介します。

しかし、今はこれらの重要な**コンセプトに基づくアイデア**を確認しましょう。これらのコンセプトは、他のどのタイプのWeb APIにも当てはまります。💡

## セキュリティ - HTTPS

<!-- NOTE: https.md written in Japanese does not exist, so it redirects to English one  -->
[前チャプターのHTTPSについて](https.md){.internal-link target=_blank}では、HTTPSがどのようにAPIを暗号化するのかについて学びました。

通常、アプリケーションサーバにとって**外部の**コンポーネントである**TLS Termination Proxy**によって提供されることが一般的です。このプロキシは通信の暗号化を担当します。

</div>

!!! tip
    Every time you install a new package with `pip` under that environment, activate the environment again.

    This makes sure that if you use a terminal program installed by that package, you use the one from your local environment and not any other that could be installed globally.

### Install requirements using pip

After activating the environment as described above:

<div class="termy">

```console

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"