UpdateItem in AWS DynamoDB using AWS Lambda (node)

Question

I'm trying to update a record in DynamoDB using Lambda (node). I can change the structure of params and get errors like Expected params.ExpressionAttributeValues[':done'] to be a structure, so I believe it's communicating with DynamoDB.

This is the params:

{
  "TableName": "test_table",
  "Key": {
      "id": {
          "S": "90c31f23-96e3-4d5d-b08d-95aafb9bed2e"
      }
  },
  "UpdateExpression": "SET done = :done",
  "ExpressionAttributeValues": {
      ":done": {
          "S": "t"
      }
  },
  "ReturnValues": "UPDATED_NEW"
}

From there it just times out, so it's hard to know what the issue is.

This is the full lambda function:

var aws = require('aws-sdk');
var dynamodb = new aws.DynamoDB({
  apiVersion: '2012-08-10',
  accessKeyId: 'xxx',
  secretAccesskey: 'xxx',
  region: 'us-west-2'
})

exports.handler = (event, context, callback) => {
    console.log('Incoming: ', event);

    var table = "test_table";

    event.Records.forEach((record) => {
      console.log('DynamoDB Record: %j', record.dynamodb);

      var params = {
        TableName: table,
        Key: {
          "id": record.dynamodb.Keys.id
        },
        UpdateExpression: "SET done = :done",
        ExpressionAttributeValues: {
          ":done": { "S": "t" }
        },
        ReturnValues: "UPDATED_NEW"
      };

      console.log("params: %j", params);

      dynamodb.updateItem(params, function(err, data) {
        if (err) console.log("Unable to update item. Error: ", JSON.stringify(err, null, 2));
        else console.log("Updated item succeeded: ", JSON.stringify(data, null, 2));
      });
    });
    callback(null, "Successfully processed ${event.Records.length} records.");
};

is it correct that the message is not intended to create a table, and rather update a document to a pre-existing table ? if so, would you please include the create table info — aug2uag
I'm using rails with dynamoid which creates the table. Is there something in particular you're wondering about? — Archonic
the Schemas are strict, judging by the looks it needs to be an exact match .. check out the low level type system — aug2uag

aug2uag aug2uag · Accepted Answer · 2016-05-17T02:04:09

according to the docs, you'd have to have a Document Client, and refine your flow control ..

var aws = require('aws-sdk');
var dynamodb = new aws.DynamoDB({
  apiVersion: '2012-08-10',
  accessKeyId: 'xxx',
  secretAccesskey: 'xxx',
  region: 'us-west-2'
})

exports.handler = (event, context, callback) => {
    console.log('Incoming: ', event);

    var table = "test_table";
    var docClient = new dynamodb.DocumentClient()

    function async(record, next) {
        var params = {
            TableName: table,
            Key: {
                "id": record.dynamodb.Keys.id
            },
            UpdateExpression: "SET done = :done",
            ExpressionAttributeValues: {
                ":done": { "S": "t" }
            },
            ReturnValues: "UPDATED_NEW"
        };

        console.log("params: %j", params);

        docClient.updateItem(params, function(err, data) {
            if (err) console.log("Unable to update item. Error: ", JSON.stringify(err, null, 2));
            else console.log("Updated item succeeded: ", JSON.stringify(data, null, 2));
            next() // modify for err handling
        });
    }
    function final() { callback(null, "Successfully processed ${event.Records.length} records."); }

    var results = [];

    event.Records.forEach(function(item) {
        async(item, function(){
            results.push(true);
            if(results.length == event.Records.length) final();
        });
    });
};

UpdateItem in AWS DynamoDB using AWS Lambda (node)

1 Answers