# Extending OpenAPI

There are some cases where you might need to modify the generated OpenAPI schema.

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.

## Conditional OpenAPI from settings and env vars

You can easily use the same Pydantic settings to configure your generated OpenAPI and the docs UIs.

For example:

{* ../../docs_src/conditional_openapi/tutorial001.py hl[6,11] *}

Here we declare the setting `openapi_url` with the same default of `"/openapi.json"`.

And then we use it when creating the `FastAPI` app.

## Documenting webhooks with **FastAPI** and OpenAPI

With **FastAPI**, using OpenAPI, you can define the names of these webhooks, the types of HTTP operations that your app can send (e.g. `POST`, `PUT`, etc.) and the request **bodies** that your app would send.

* A *rota* pode conter uma <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression" class="external-link" target="_blank">expressão OpenAPI 3</a> (veja mais abaixo) onde pode usar variáveis com parâmetros e partes da solicitação original enviada para *sua API*.

### A expressão do caminho do callback

# Separate OpenAPI Schemas for Input and Output or Not

When using **Pydantic v2**, the generated OpenAPI is a bit more exact and **correct** than before. 😎

In fact, in some cases, it will even have **two JSON Schemas** in OpenAPI for the same Pydantic model, for input and output, depending on if they have **default values**.

Let's see how that works and how to change it if you need to do that.

## Pydantic Models for Input and Output

Então, o frontend (que roda no navegador) tentaria acessar `/openapi.json` e não conseguiria obter o OpenAPI schema.

Como temos um proxy com um prefixo de caminho de `/api/v1` para nossa aplicação, o frontend precisa buscar o OpenAPI schema em `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Browser")

예를 들어, 알파벳 순서상 `users`는 `items` 뒤에 오지만, 우리는 `users` 메타데이터를 리스트의 첫 번째 딕셔너리로 추가했기 때문에 먼저 표시됩니다.

## OpenAPI URL

OpenAPI 구조는 기본적으로  `/openapi.json`에서 제공됩니다.

`openapi_url` 매개변수를 통해 이를 설정할 수 있습니다.

예를 들어, 이를 `/api/v1/openapi.json`에 제공하도록 설정하려면:

```Python hl_lines="3"
{!../../docs_src/metadata/tutorial002.py!}
```

OpenAPI 구조를 완전히 비활성화하려면 `openapi_url=None`으로 설정할 수 있으며, 이를 사용하여 문서화 사용자 인터페이스도 비활성화됩니다.

## 문서화 URL

#### OpenAPI i JSON Schema

OpenAPI definiuje API Schema dla Twojego API, który zawiera definicje (lub "schematy") danych wysyłanych i odbieranych przez Twój interfejs API przy użyciu **JSON Schema**, standardu dla schematów danych w formacie JSON.

#### Sprawdź `openapi.json`

<img src="/img/tutorial/extending-openapi/image02.png">

But you can disable it by setting `syntaxHighlight` to `False`:

{* ../../docs_src/configure_swagger_ui/tutorial001.py hl[3] *}

...and then Swagger UI won't show the syntax highlighting anymore:

<img src="/img/tutorial/extending-openapi/image03.png">

## Change the Theme

## More information about OpenAPI responses

To see what exactly you can include in the responses, you can check these sections in the OpenAPI specification:

* <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#responses-object" class="external-link" target="_blank">OpenAPI Responses Object</a>, it includes the `Response Object`.