* 以 JSON 形式读取请求体
* （在必要时）把请求体转换为对应的类型
* 校验数据：
    * 数据无效时返回错误信息，并指出错误数据的确切位置和内容
* 把接收的数据赋值给参数 `item`
    * 把函数中请求体参数的类型声明为 `Item`，还能获得代码补全等编辑器支持
* 为模型生成 <a href="https://json-schema.org" class="external-link" target="_blank">JSON Schema</a>，在项目中所需的位置使用
* 这些概图是 OpenAPI 概图的部件，用于 API 文档 <abbr title="用户界面">UI</abbr>

## API 文档

Pydantic 模型的 JSON 概图是 OpenAPI 生成的概图部件，可在 API 文档中显示：

<img src="/img/tutorial/body/image01.png">

///

FastAPI will now:

* **Validate** the data making sure that the max length is 50 characters
* Show a **clear error** for the client when the data is not valid
* **Document** the parameter in the OpenAPI schema *path operation* (so it will show up in the **automatic docs UI**)

## Alternative (old): `Query` as the default value { #alternative-old-query-as-the-default-value }

* Add a **JSON Schema** for the response, in the OpenAPI *path operation*.
    * This will be used by the **automatic docs**.
    * It will also be used by automatic client code generation tools.

But most importantly:

///

## OpenAPI and API docs { #openapi-and-api-docs }

If you return additional status codes and responses directly, they won't be included in the OpenAPI schema (the API docs), because FastAPI doesn't have a way to know beforehand what you are going to return.

package schema

import (
	"context"
	"math"
	"reflect"
	"testing"
	"time"
)

func TestUnixSecondSerializer_Value(t *testing.T) {
	var (
		intValue      = math.MaxInt64
		int8Value     = int8(math.MaxInt8)
		int16Value    = int16(math.MaxInt16)
		int32Value    = int32(math.MaxInt32)
		int64Value    = int64(math.MaxInt64)
		uintValue     = uint(math.MaxInt64)
		uint8Value    = uint8(math.MaxUint8)

* Ciência de Dados
* Deep Learning
* Aprendizado de Máquina
* Injeção de Dependências
* autenticação HTTP Basic
* HTTP Digest
* formato ISO
* o padrão JSON Schema
* o JSON schema
* a definição do schema
* Fluxo de Senha
* Mobile

* descontinuado
* projetado
* inválido
* dinamicamente
* padrão
* padrão predefinido
* sensível a maiúsculas e minúsculas

{* ../../docs_src/body_nested_models/tutorial005_py310.py hl[2,8] *}

The string will be checked to be a valid URL, and documented in JSON Schema / OpenAPI as such.

## Attributes with lists of submodels { #attributes-with-lists-of-submodels }

You can also use Pydantic models as subtypes of `list`, `set`, etc.:

* Добавления **JSON Schema** для ответа в OpenAPI *операции пути*.
    * Это будет использовано **автоматической документацией**.
    * Это также будет использовано инструментами автоматической генерации клиентского кода.

Но самое главное:

///

## OpenAPI- und API-Dokumentation { #openapi-and-api-docs }

Wenn Sie zusätzliche Statuscodes und Responses direkt zurückgeben, werden diese nicht in das OpenAPI-Schema (die API-Dokumentation) aufgenommen, da FastAPI keine Möglichkeit hat, im Voraus zu wissen, was Sie zurückgeben werden.

///

It will:

* Return that status code in the response.
* Document it as such in the OpenAPI schema (and so, in the user interfaces):

<img src="/img/tutorial/response-status-code/image01.png">

/// note

Some response codes (see the next section) indicate that the response does not have a body.