Node.js- 扫描 DynamoDB AWS- 添加参数

Question

我使用 Lambda AWS 从 dynamoDB 获取数据。我尝试将参数添加到我从 android app:

发送到 Lambda 的参数中

if (typeof event.high_lat != "undefined") {
            params.ExpressionAttributeValues = event.high_lat;
        }

但是我得到一个错误：

 [InvalidParameterType: Expected params.ExpressionAttributeValues to be a map]
  message: 'Expected params.ExpressionAttributeValues to be a map',

有人知道怎么解决吗？

我的全部代码：

var AWS = require('aws-sdk');
var db = new AWS.DynamoDB();

exports.handler = function(event, context) {


   var params = {
    TableName: "Events", //"StreamsLambdaTable",
    ProjectionExpression: "ID, description, endDate, imagePath, locationLat, locationLon, #nm, startDate, #tp, userLimit",  //specifies the attributes you want in the scan result.
    FilterExpression: "locationLon between :lower_lon and :higher_lon and locationLat between :lower_lat and :higher_lat",
    ExpressionAttributeNames: {
        "#nm": "name",
        "#tp": "type",
    },

     ExclusiveStartKey: {
       "ID": {"S": event.LastEvaluatedKey}
     },

    ExpressionAttributeValues: {
        ":lower_lon": {"N": event.low_lon},
        ":higher_lon": {"N": event.high_lon}, 
        ":lower_lat": {"N": event.low_lat}
    }
};


if (typeof event.high_lat != "undefined") {
            params.ExpressionAttributeValues = event.high_lat;
        }


  db.scan(params, function(err, data) {
    if (err) {
      console.log(err); // an error occurred
      } 
    else {
      data.Items.forEach(function(record) {
           console.log(
                record.name.S + "");
        });
        context.succeed(data.Items);


      }
  });
};

从 android 应用发送的代码示例：

{
  "low_lon": "16",
  "high_lon": "17",
  "low_lat": "52",
  "high_lat": "53"
}

Answer 1

您正在用单个值吹走整个 ExpressionAttributeValues 映射。您只需查看上面编写的代码，了解应如何向 ExpressionAttributeValues 映射添加值。

改变这个：

params.ExpressionAttributeValues = event.high_lat;

为此：

params.ExpressionAttributeValues[":higher_lat"] = {"N": event.high_lat};

Node.js- 扫描 DynamoDB AWS- 添加参数

Node.js- scan DynamoDB AWS- adding parameters

amazon-web-services

node.js

aws-lambda