Node.js-扫描DynamoDB AWS-添加参数

Question

我使用Lambda AWS从dynamoDB获取数据。我尝试参数添加到我的参数，我送拉姆达从Android应用：

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

但我得到一个错误：

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

有谁知道如何解决呢？

我的整个代码：从Android应用程序发送的代码

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); 


     } 
    }); 
}; 

例子：

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

Answer 1

你吹走你的整个ExpressionAttributeValues地图的单个值。你只需要看看你上面写的代码，看看你应该如何给ExpressionAttributeValues映射添加值。

更改此：

params.ExpressionAttributeValues = event.high_lat; 

要这样：

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