# 模式的额外信息 - 例子

您可以在JSON模式中定义额外的信息。

一个常见的用例是添加一个将在文档中显示的`example`。

有几种方法可以声明额外的 JSON 模式信息。

## Pydantic `schema_extra`

您可以使用 `Config` 和 `schema_extra` 为Pydantic模型声明一个示例，如<a href="https://docs.pydantic.dev/latest/concepts/json_schema/#schema-customization" class="external-link" target="_blank">Pydantic 文档：定制 Schema </a>中所述:

//// tab | Python 3.10+

```Python hl_lines="13-21"
{!> ../../docs_src/schema_extra_example/tutorial001_py310.py!}

  // serving write operations, so that this field will be in sync with the reality.
  // +optional
  optional string commonEncodingVersion = 2;

  // The latest available observations of the storageVersion's state.
  // +optional
  // +listType=map
  // +listMapKey=type
  repeated StorageVersionCondition conditions = 3;

Bucket events can be published to the following targets:

| Supported Notification Targets    |                             |                                 |

//// tab | Pydantic v2

In Pydantic version 2, you would use the attribute `model_config`, that takes a `dict` as described in <a href="https://docs.pydantic.dev/latest/api/config/" class="external-link" target="_blank">Pydantic's docs: Configuration</a>.

func (r *Reader) SetExpectedMax(expectedMax int64) {
	r.expectedMax = expectedMax
}

// AddChecksum will add checksum checks as specified in
// https://docs.aws.amazon.com/AmazonS3/latest/userguide/checking-object-integrity.html
// Returns ErrInvalidChecksum if a problem with the checksum is found.
func (r *Reader) AddChecksum(req *http.Request, ignoreValue bool) error {
	cs, err := GetContentChecksum(req.Header)

## Pydantic `Settings`

Por sorte, o Pydantic possui uma funcionalidade para lidar com essas configurações vindas de variáveis de ambiente utilizando <a href="https://docs.pydantic.dev/latest/usage/pydantic_settings/" class="external-link" target="_blank">Pydantic: Settings management</a>.

### Instalando `pydantic-settings`

Primeiro, instale o pacote `pydantic-settings`:

<div class="termy">

}

// STSErrorCode type of error status.
type STSErrorCode int

//go:generate stringer -type=STSErrorCode -trimprefix=Err $GOFILE

// Error codes, non exhaustive list - http://docs.aws.amazon.com/STS/latest/APIReference/API_AssumeRoleWithSAML.html
const (
	ErrSTSNone STSErrorCode = iota
	ErrSTSAccessDenied
	ErrSTSMissingParameter
	ErrSTSInvalidParameterValue
	ErrSTSWebIdentityExpiredToken
	ErrSTSClientGrantsExpiredToken

			CipherSuites:             fips.TLSCiphersBackwardCompatible(),
			CurvePreferences:         fips.TLSCurveIDs(),
		}
		// This is only to support client side certificate authentication
		// https://coreos.com/etcd/docs/latest/op-guide/security.html
		etcdClientCertFile := env.Get(EnvEtcdClientCert, kvs.Get(ClientCert))
		etcdClientCertKey := env.Get(EnvEtcdClientCertKey, kvs.Get(ClientCertKey))
		if etcdClientCertFile != "" && etcdClientCertKey != "" {

			log.Warnf("failed to read proc %v stats: %v", p.PID, err)
			if best == "" {
				best = ns
			}
			continue
		}
		// Get the oldest one.
		if s.Starttime < oldest {
			oldest = s.Starttime
			best = ns
		}
	}
	if best == "" {
		return "", fmt.Errorf("failed to find network namespace")
	}
	return best, nil

这意味着从环境变量中在 Python 中读取的任何值都将是 `str` 类型，任何类型的转换或验证都必须在代码中完成。

## Pydantic 的 `Settings`

幸运的是，Pydantic 提供了一个很好的工具来处理来自环境变量的设置，即<a href="https://docs.pydantic.dev/latest/concepts/pydantic_settings/" class="external-link" target="_blank">Pydantic: Settings management</a>。

### 创建 `Settings` 对象

从 Pydantic 导入 `BaseSettings` 并创建一个子类，与 Pydantic 模型非常相似。