向用户发送个性化电子邮件

此 query 检索用户列表，获取每位用户的数据（姓名、电子邮件地址以及以元数据形式存储的剩余积分数），并向每位用户发送个性化电子邮件。

此 query 需要在端点上启用嵌套 Mutation。

mutation SendPersonalizedEmailToUsers {
  users {
    email
    displayName
    credits: metaValue(key: "credits")
    
    # If the user does not have meta entry "credits", use `0` credits
    hasNoCreditsEntry: _isNull(value: $__credits)
    remainingCredits: _if(condition: $__hasNoCreditsEntry, then: 0, else: $__credits)
 
    emailMessageTemplate: _strConvertMarkdownToHTML(
      text: """
 
Hello %s,
 
Your have **%s remaining credits** in your account.
 
Would you like to [buy more](%s)?
 
      """
    )
    emailMessage: _sprintf(
      string: $__emailMessageTemplate,
      values: [
        $__displayName,
        $__remainingCredits,
        "https://mysite.com/buy-credits"
      ]
    )
 
    _sendEmail(
      input: {
        to: $__email
        subject: "Remaining credits alert"
        messageAs: {
          html: $__emailMessage
        }
      }
    ) {
      status
      errors {
        __typename
        ...on ErrorPayload {
          message
        }
      }
    }
  }
}