# 교차 출처 리소스 공유

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS 또는 "교차-출처 리소스 공유"</a>란, 브라우저에서 동작하는 프론트엔드가 자바스크립트로 코드로 백엔드와 통신하고, 백엔드는 해당 프론트엔드와 다른 "출처"에 존재하는 상황을 의미합니다.

## 출처

출처란 프로토콜(`http` , `https`), 도메인(`myapp.com`, `localhost`, `localhost.tiangolo.com` ), 그리고 포트(`80`, `443`, `8080` )의 조합을 의미합니다.

따라서, 아래는 모두 상이한 출처입니다:

* `http://localhost`
* `https://localhost`

It will be defined in OpenAPI with `anyOf`.

To do that, use the standard Python type hint <a href="https://docs.python.org/3/library/typing.html#typing.Union" class="external-link" target="_blank">`typing.Union`</a>:

/// note

   * more futures or adding more {@code directExecutor()} listeners inline -- consider {@link
   * MoreExecutors#directExecutor}. Otherwise, avoid it: See the warnings on the docs for {@code
   * directExecutor}.
   *
   * <p>This is the most general listener interface. For common operations performed using
   * listeners, see {@link Futures}. For a simplified but general listener interface, see {@link

In this example, it would convert the Pydantic model to a `dict`, and the `datetime` to a `str`.

The result of calling it is something that can be encoded with the Python standard <a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>.

 & `Response` 💪 ⚙️ 🛎 ⚒ 🎚 & 🍪, **FastAPI** 🚚 ⚫️ `fastapi.Response`.

///

## 🛃 🎚

✔️ 🤯 👈 🛃 © 🎚 💪 🚮 <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">⚙️ '✖-' 🔡</a>.

Neste exemplo, ele converteria o modelo Pydantic em um `dict`, e o `datetime` em um `str`.

O resultado de chamar a função é algo que pode ser codificado com o padrão do Python <a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>.

### Checando a documentação

Você pode ver os headers necessários na interface gráfica da documentação em `/docs`:

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

### Proibindo Cabeçalhos adicionais

                <arg>--add-reads=com.google.common=ALL-UNNAMED</arg>
                <arg>--add-reads=com.google.common.testlib=ALL-UNNAMED</arg>
                <!-- https://errorprone.info/docs/installation#maven -->
                <arg>-XDcompilePolicy=simple</arg>
                <arg>-Xlint:-removal</arg>
                <arg>-Xlint:-options</arg>
              </compilerArgs>

                <arg>--add-reads=com.google.common=ALL-UNNAMED</arg>
                <arg>--add-reads=com.google.common.testlib=ALL-UNNAMED</arg>
                <!-- https://errorprone.info/docs/installation#maven -->
                <arg>-XDcompilePolicy=simple</arg>
                <arg>-Xlint:-removal</arg>
                <arg>-Xlint:-options</arg>
              </compilerArgs>

そのために`jsonable_encoder`を使用することができます。

Pydanticモデルのようなオブジェクトを受け取り、JSON互換版を返します:

{* ../../docs_src/encoder/tutorial001.py hl[5,22] *}

この例では、Pydanticモデルを`dict`に、`datetime`を`str`に変換します。

呼び出した結果は、Pythonの標準の<a href="https://docs.python.org/3/library/json.html#json.dumps" class="external-link" target="_blank">`json.dumps()`</a>でエンコードできるものです。

これはJSON形式のデータを含む大きな`str`を（文字列として）返しません。JSONと互換性のある値とサブの値を持つPython標準のデータ構造（例：`dict`）を返します。

/// note | 備考