API context.requestTime 的网关映射模板为空

API Gateway Mapping Template for context.requestTime is Blank

我正在尝试让 API 网关充当 DynamoDB 的代理,我目前正在测试一个简单的 POST 调用以附加 $context.requestId$context.requestTime 到我的 table。我收到以下 error 消息:

{
"__type": "com.amazon.coral.validate#ValidationException",
"message": "One or more parameter values were invalid: An AttributeValue may not contain an empty string"
} 

发送的是:

Mon Apr 15 19:10:24 UTC 2019 : Endpoint request body after transformations: {
  "TableName": "BurgerOrders",
  "Item": {
    "OrderId": {
      "S": "1f54a90b-5fb2-11e9-8b31-c9003bb71ec2"
    },
    "RequestTime": {
      "S": ""
    }
  }
}

我拥有的集成请求中的映射模板是:

{
  "TableName": "BurgerOrders",
  "Item": {
    "OrderId": {
      "S": "$context.requestId"
    },
    "RequestTime": {
      "S": "$context.requestTime"
    },
  }
}

我尝试将 $context.requestTime 更改为 $context.requestTimeEpoch,但我遇到了同样的错误。

我知道这是前一段时间发布的,但根据 AWS 开发人员的说法:

"At this time, [$context.requestTime] is only available when the API has been deployed and API call was invoked to deployed stage."

来源:https://forums.aws.amazon.com/thread.jspa?messageID=697652