在AWS Lambda中将DynamoDB数据格式化为普通JSON

6 回答

• 11

  AWS JavaScript SDK最近使用Document Client进行了更新，它完全满足您的需求 . 查看此处的公告和用法示例：http://blogs.aws.amazon.com/javascript/post/Tx1OVH5LUZAFC6T/Announcing-the-Amazon-DynamoDB-Document-Client-in-the-AWS-SDK-for-JavaScript

  回复于 2024-05-02T13:23:27+08:00
• 19

  我知道有点旧但我在节点js lambda函数中处理来自dynamoDB的流数据有同样的问题 . 我使用了@churro提出的建议

  导入sdk和输出转换器

  var AWS = require("aws-sdk");
  var parse = AWS.DynamoDB.Converter.output;
  

  使用小解释的解析功能

  exports.handler = function( event, context, callback ) {
    var docClient = new AWS.DynamoDB.DocumentClient();
    event.Records.forEach((record) => {
          console.log(record.eventID);
          console.log(record.eventName);
          console.log('DynamoDB Record:', parse({ "M": record.dynamodb.NewImage }));
      });
    callback(null, `Successfully processed ${event.Records.length} records.`);
  }
  

  希望能帮助到你

  回复于 2024-05-02T13:23:27+08:00
• -1

  实际上你应该使用AWSJavaScriptSDK中的 unmarshall 函数：

  const AWS = require("aws-sdk");
  
  exports.handler = function( event, context, callback ) {
    const newImages = event.Records.map(
          (record) => AWS.DynamoDB.Converter.unmarshall(record.dynamodb.NewImage)
    );
    console.log('Converted records', newImages);
    callback(null, `Success`);
  }
  

  回复于 2024-05-02T13:23:27+08:00
• -1

  我认为这只是每个应用程序的自定义转换练习 . 从DynamoDB的项目格式到您的应用程序格式的简单转换可能如下所示：

  var response = {...} // your response from DynamoDB
  var formattedObjects = response.videos.map(function(video) {
      return {
          "file": video.file.S,
          "id": video.id.S,
          "canvas": video.canvas.S
      };
  });
  

  如果要为此构建通用系统，则必须处理DynamoDB的各种AttributeValue types . 像下面这样的函数可以完成这项工作，但是我更复杂的属性值类型：

  function dynamoItemToPlainObj(dynamoItem) {
      var plainObj = {};
      for (var attributeName in dynamoItem) {
          var attribute = dynamoItem[attributeName];
          var attributeValue;
          for (var itemType in attribute) {
              switch (itemType) {
              case "S":
                  attributeValue = attribute.S.toString();
                  break;
              case "N":
                  attributeValue = Number(attribute.N);
                  break;
                  // more attribute types...
              default:
                  attributeValue = attribute[itemType].toString();
                  break;
              }
          }
          plainObj[attributeName] = attributeValue;
      }
      return plainObj;
  }    
  var formattedObjects = response.videos.map(dynamoItemToPlainObj);
  

  回复于 2024-05-02T13:23:27+08:00
• -1

  如果您需要在线编辑器试试这个

  https://2json.net/dynamo

  回复于 2024-05-02T13:23:27+08:00
• 15

  在这里你可以找到这样做的要点：

  function mapper(data) {
  
  let S = "S";
  let SS = "SS";
  let NN = "NN";
  let NS = "NS";
  let BS = "BS";
  let BB = "BB";
  let N = "N";
  let BOOL = "BOOL";
  let NULL = "NULL";
  let M = "M";
  let L = "L";
  
  if (isObject(data)) {
      let keys = Object.keys(data);
      while (keys.length) {
          let key = keys.shift();
          let types = data[key];
  
          if (isObject(types) && types.hasOwnProperty(S)) {
              data[key] = types[S];
          } else if (isObject(types) && types.hasOwnProperty(N)) {
              data[key] = parseFloat(types[N]);
          } else if (isObject(types) && types.hasOwnProperty(BOOL)) {
              data[key] = types[BOOL];
          } else if (isObject(types) && types.hasOwnProperty(NULL)) {
              data[key] = null;
          } else if (isObject(types) && types.hasOwnProperty(M)) {
              data[key] = mapper(types[M]);
          } else if (isObject(types) && types.hasOwnProperty(L)) {
              data[key] = mapper(types[L]);
          } else if (isObject(types) && types.hasOwnProperty(SS)) {
              data[key] = types[SS];
          } else if (isObject(types) && types.hasOwnProperty(NN)) {
              data[key] = types[NN];
          } else if (isObject(types) && types.hasOwnProperty(BB)) {
              data[key] = types[BB];
          } else if (isObject(types) && types.hasOwnProperty(NS)) {
              data[key] = types[NS];
          } else if (isObject(types) && types.hasOwnProperty(BS)) {
              data[key] = types[BS];
          }
      }
  }
  
  
  return data;
  
  function isObject(value) {
      return typeof value === "object" && value !== null;
  }
  

  }

  https://gist.github.com/igorzg/c80c0de4ad5c4028cb26cfec415cc600

  回复于 2024-05-02T13:23:27+08:00