### OpenAPI

**FastAPI** generiert ein „Schema“ mit all Ihren APIs unter Verwendung des **OpenAPI**-Standards zur Definition von APIs.

#### „Schema“

Ein „Schema“ ist eine Definition oder Beschreibung von etwas. Nicht der eigentliche Code, der es implementiert, sondern lediglich eine abstrakte Beschreibung.

#### API-„Schema“

This schema definition includes your API paths, the possible parameters they take, etc.

#### Data "schema"

The term "schema" might also refer to the shape of some data, like a JSON content.

In that case, it would mean the JSON attributes, and data types they have, etc.

#### OpenAPI and JSON Schema

It used custom types in its declarations instead of standard Python types, but it was still a huge step forward.

It also was one of the first frameworks to generate a custom schema declaring the whole API in JSON.

It was not based on a standard like OpenAPI and JSON Schema. So it wouldn't be straightforward to integrate it with other tools, like Swagger UI. But again, it was a very innovative idea.

You can declare extra information in `Field`, `Query`, `Body`, etc. And it will be included in the generated JSON Schema.

You will learn more about adding extra information later in the docs, when learning to declare examples.

!!! warning
    Extra keys passed to `Field` will also be present in the resulting OpenAPI schema for your application.

    **FastAPI** prendra le modèle Pydantic à partir de là, générera le `JSON Schema` et le placera au bon endroit.

    Le bon endroit est :

    * Dans la clé `content`, qui a pour valeur un autre objet JSON (`dict`) qui contient :
        * Une clé avec le type de support, par ex. `application/json`, qui contient comme valeur un autre objet JSON, qui contient :
            * Une clé `schema`, qui a pour valeur le schéma JSON du modèle, voici le bon endroit.

So, the frontend (that runs in the browser) would try to reach `/openapi.json` and wouldn't be able to get the OpenAPI schema.

Because we have a proxy with a path prefix of `/api/v1` for our app, the frontend needs to fetch the OpenAPI schema at `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Browser")

## Adicione informações extras

Você pode declarar informação extra em `Field`, `Query`, `Body`, etc. E isso será incluído no JSON Schema gerado.

Você irá aprender mais sobre adicionar informações extras posteriormente nessa documentação, quando estiver aprendendo a declarar exemplos.

## Recapitulando

* Tự động tài liệu hóa data model theo <a href="https://json-schema.org/" class="external-link" target="_blank"><strong>JSON Schema</strong></a> (OpenAPI bản thân nó được dựa trên JSON Schema).
* Được thiết kế xung quanh các tiêu chuẩn này sau khi nghiên cứu tỉ mỉ thay vì chỉ suy nghĩ đơn giản và sơ xài.

    注意，模型属性的类型、默认值及 `Field` 的代码结构与*路径操作函数*的参数相同，只不过是用 `Field` 替换了`Path`、`Query`、`Body`。

## 添加更多信息

`Field`、`Query`、`Body` 等对象里可以声明更多信息，并且 JSON Schema 中也会集成这些信息。

*声明示例*一章中将详细介绍添加更多信息的知识。

## 小结

Pydantic 的 `Field` 可以为模型属性声明更多校验和元数据。

`FastAPI` 🈸 (👐) ✔️ `.openapi()` 👩‍🔬 👈 📈 📨 🗄 🔗.

🍕 🈸 🎚 🏗, *➡ 🛠️* `/openapi.json` (⚖️ ⚫️❔ 👆 ⚒ 👆 `openapi_url`) ®.

⚫️ 📨 🎻 📨 ⏮️ 🏁 🈸 `.openapi()` 👩‍🔬.

🔢, ⚫️❔ 👩‍🔬 `.openapi()` 🔨 ✅ 🏠 `.openapi_schema` 👀 🚥 ⚫️ ✔️ 🎚 & 📨 👫.

🚥 ⚫️ 🚫, ⚫️ 🏗 👫 ⚙️ 🚙 🔢 `fastapi.openapi.utils.get_openapi`.

& 👈 🔢 `get_openapi()` 📨 🔢:

* `title`: 🗄 📛, 🎦 🩺.
* `version`: ⏬ 👆 🛠️, ✅ `2.5.0`.