# OpenAPI erweitern

In einigen Fällen müssen Sie möglicherweise das generierte OpenAPI-Schema ändern.

In diesem Abschnitt erfahren Sie, wie.

## Der normale Vorgang

Der normale (Standard-)Prozess ist wie folgt.

Eine `FastAPI`-Anwendung (-Instanz) verfügt über eine `.openapi()`-Methode, von der erwartet wird, dass sie das OpenAPI-Schema zurückgibt.

## 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.

* The *path* can contain an <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.1.0.md#key-expression" class="external-link" target="_blank">OpenAPI 3 expression</a> (see more below) where it can use variables with parameters and parts of the original request sent to *your API*.

### The callback path expression

* 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

```

📥 👥 📣 ⚒ `openapi_url` ⏮️ 🎏 🔢 `"/openapi.json"`.

& ⤴️ 👥 ⚙️ ⚫️ 🕐❔ 🏗 `FastAPI` 📱.

⤴️ 👆 💪 ❎ 🗄 (✅ 🎚 🩺) ⚒ 🌐 🔢 `OPENAPI_URL` 🛁 🎻, 💖:

<div class="termy">

```console
$ OPENAPI_URL= uvicorn main:app

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

</div>

*  *➡* 💪 🔌 <a href="https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#key-expression" class="external-link" target="_blank">🗄 3️⃣ 🧬</a> (👀 🌖 🔛) 🌐❔ ⚫️ 💪 ⚙️ 🔢 ⏮️ 🔢 &amp; 🍕 ⏮️ 📨 📨 *👆 🛠️*.

### ⏲ ➡ 🧬

# 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

# Esquemas OpenAPI Separados para Entrada e Saída ou Não

Ao usar **Pydantic v2**, o OpenAPI gerado é um pouco mais exato e **correto** do que antes. 😎

Inclusive, em alguns casos, ele terá até **dois JSON Schemas** no OpenAPI para o mesmo modelo Pydantic, para entrada e saída, dependendo se eles possuem **valores padrão**.

Vamos ver como isso funciona e como alterar se for necessário.

## Modelos Pydantic para Entrada e Saída

openapi: 3.0.3
info:
  title: Fess - User API
  description: |-
    This is a Fess Server based on the OpenAPI 3.0 specification.  
  license:
    name: Apache 2.0
    url: http://www.apache.org/licenses/LICENSE-2.0.html
  version: 14.8.0
externalDocs:
  description: API Documentation
  url: https://fess.codelibs.org/14.8/api/
servers:
  - url: http://localhost:8080/api/v1
tags:
  - name: search
    description: Search operations