* 把接收的数据赋值给参数 `item`。
    * 因为你把函数中的参数类型声明为 `Item`，所以还能获得所有属性及其类型的编辑器支持（补全等）。
* 为你的模型生成 [JSON Schema](https://json-schema.org) 定义，如果对你的项目有意义，还可以在其他地方使用它们。
* 这些 schema 会成为生成的 OpenAPI Schema 的一部分，并被自动文档的 <abbr title="User Interfaces - 用户界面">UIs</abbr> 使用。

## 自动文档 { #automatic-docs }

你的模型的 JSON Schema 会成为生成的 OpenAPI Schema 的一部分，并显示在交互式 API 文档中：

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

并且，还会用于需要它们的每个*路径操作*的 API 文档中：

{
  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
  "extends": [
    "config:recommended",
    "group:monorepos",
    "group:recommended",
    ":dependencyDashboard"
  ],
  "semanticCommits": "disabled",
  "labels": [
    "renovate"
  ],
  "ignoreDeps": [
    "com.squareup.okhttp3:okhttp",
    "com.squareup.okhttp3:okhttp-tls",
    "com.squareup.okhttp3:mockwebserver"
  ],
  "packageRules": [
    {

        return app.openapi_schema
    openapi_schema = get_openapi(
        title="Custom title",
        version="2.5.0",
        summary="This is a very custom OpenAPI schema",
        description="Here's a longer description of the custom **OpenAPI** schema",
        routes=app.routes,
    )
    openapi_schema["info"]["x-logo"] = {
        "url": "https://fastapi.tiangolo.com/img/logo-margin/logo-teal.png"
    }

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.

/// warning | Atenção

Chaves extras passadas para `Field` também estarão presentes no schema OpenAPI resultante da sua aplicação.

### Сгенерируйте схему OpenAPI { #generate-the-openapi-schema }

Затем используйте ту же вспомогательную функцию для генерации схемы OpenAPI внутри функции `custom_openapi()`:

{* ../../docs_src/extending_openapi/tutorial001_py310.py hl[2,15:21] *}

### Измените схему OpenAPI { #modify-the-openapi-schema }

### OpenAPI Şemasını Üretme { #generate-the-openapi-schema }

Ardından, bir `custom_openapi()` fonksiyonunun içinde aynı yardımcı fonksiyonu kullanarak OpenAPI şemasını üretin:

{* ../../docs_src/extending_openapi/tutorial001_py310.py hl[2,15:21] *}

### OpenAPI Şemasını Değiştirme { #modify-the-openapi-schema }

Type\":\"date_histogram\"},\"y\":[{\"accessor\":1,\"format\":{\"id\":\"number\"},\"params\":{},\"aggType\":\"count\"}]}},\"aggs\":[{\"id\":\"1\",\"enabled\":true,\"type\":\"count\",\"schema\":\"metric\",\"params\":{\"customLabel\":\"Query Count\"}},{\"id\":\"2\",\"enabled\":true,\"type\":\"date_histogram\",\"schema\":\"segment\",\"params\":{\"field\":\"requestedAt\",\"timeRange\":{\"from\":\"now-2d\",\"to\":\"now\"},\"useNormalizedEsInterval\":true,\"interval\":\"s\",\"drop_partials\":false,\"mi...

		}
		tx = tx.callbacks.Create().Execute(tx.Set("gorm:update_track_time", true))
	case reflect.Struct:
		if err := tx.Statement.Parse(value); err == nil && tx.Statement.Schema != nil {
			for _, pf := range tx.Statement.Schema.PrimaryFields {
				if _, isZero := pf.ValueOf(tx.Statement.Context, reflectValue); isZero {
					return tx.callbacks.Create().Execute(tx)
				}
			}
		}

		fallthrough
	default:

	"testing"

	"gorm.io/gorm"
	"gorm.io/gorm/clause"
	"gorm.io/gorm/schema"
	"gorm.io/gorm/utils/tests"
)

var db, _ = gorm.Open(tests.DummyDialector{}, nil)

func checkBuildClauses(t *testing.T, clauses []clause.Interface, result string, vars []interface{}) {
	var (
		buildNames    []string
		buildNamesMap = map[string]bool{}
		user, _       = schema.Parse(&tests.User{}, &sync.Map{}, db.NamingStrategy)

)
def test_optional_str_schema(path: str):
    assert app.openapi()["paths"][path]["get"]["parameters"] == snapshot(
        [
            {
                "required": False,
                "schema": {
                    "anyOf": [{"type": "string"}, {"type": "null"}],
                    "title": "P",
                },
                "name": "p",
                "in": "cookie",
            }
        ]