AWS Lambda function write to DynamoDB

Question

I'm a beginner with Amazon Web Services and NodeJS.

I wrote a Lambda function, triggered by AWS IoT, that parse a JSON.

enter code here
use strict';

console.log('Loading function');

exports.handler = (event, context, callback) => {
   console.log('Received event:', JSON.stringify(event, null, 2));
   console.log('Id =', event.Id);
   console.log('Ut =', event.Ut);
   console.log('Temp =', event.Temp);
   console.log('Rh =', event.Rh);
   //callback(null, event.key1);  // Echo back the first key value
   //callback('Something went wrong');
};

Now I want to store the json fields into a DynamoDB table.

Any suggestion?

Thanks a lot!

notionquest · Accepted Answer · 2017-03-06 15:04:53Z

20

Preliminary Steps:-

Create an IAM Lambda role with access to dynamodb
Launch Lambda in the same region as your dynamodb region
Create the DynamoDB table with correct key attributes defined

Sample code:-

The below code snippet is a sample code to give you some idea on how to put the item. Please note that it has to be slightly altered for your requirement (with table name and key attributes). It is not fully tested code.

use strict';

console.log('Loading function');
var AWS = require('aws-sdk');
var dynamodb = new AWS.DynamoDB({apiVersion: '2012-08-10'});

exports.handler = (event, context, callback) => {
    console.log(JSON.stringify(event, null, '  '));
    var tableName = "yourtablename";    
    dynamodb.putItem({
        "TableName": tableName,
        "Item" : {
            "Id": event.Id,
            "Ut": event.Ut,
            "Temp": event.Temp,
            "Rh":event.Rh
        }
    }, function(err, data) {
        if (err) {
            console.log('Error putting item into dynamodb failed: '+err);
            context.done('error');
        }
        else {
            console.log('great success: '+JSON.stringify(data, null, '  '));
            context.done('Done');
        }
    });
};

Note:-

No need to mention the data type explicitly for String and Number as long as the data type is in compliance with JavaScript String and Number. The DynamoDB will automatically interpret the data type for String and Number.

edited Mar 6, 2017 at 15:04

answered Mar 6, 2017 at 10:35

notionquest

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10 Comments

Federico Over a year ago

Thanks for the reply. I create a DynamoDB Table with primary Key: "Id" and Order Key: "Ut" both are strings. I create a role in IAM for Lambda with full access to DynamoDb. Unfortunately i get an error: { errorMessage": "error"}

Federico Over a year ago

This is the error: Error putting item into dynamodb failed: MultipleValidationErrors: There were 3 validation errors: * InvalidParameterType: Expected params.Item['Ut'].S to be a string * InvalidParameterType: Expected params.Item['Temp'].S to be a string * InvalidParameterType: Expected params.Item['Rh'].S to be a string

notionquest Over a year ago

This seems to be a problem with the event data. Please could you check the event json whether Rh and Temp are String data types? The JSON that you use to trigger the Lambda should have these attribute value as String (i.e. with double quotes) rather than a number or date or anything else.

Federico Over a year ago

These values into the Json are number fields. Is possible to store these values ad integer or float into DynamoDb?

Federico Over a year ago

Same error: * InvalidParameterType: Expected params.Item['Ut'].N to be a string * InvalidParameterType: Expected params.Item['Temp'].N to be a string * InvalidParameterType: Expected params.Item['Rh'].N to be a string. This is the json that trigger the lambda: { "Id": "Id", "Ut": 1488810488, "Temp": 22.6, "Rh": 57.08 }

|

PersianIronwood · Accepted Answer · 2020-04-05 22:35:16Z

7

There is also a shorter version for this with async/await:

'use strict';

const AWS = require('aws-sdk');
const dynamodb = new AWS.DynamoDB({apiVersion: '2012-08-10'});

exports.handler = async (event) => {
    const tableName = "yourtablename"; 
    try {
      await dynamodb.putItem({
          "TableName": tableName,
          "Item" : {
              "Id": event.Id,
              "Ut": event.Ut,
              "Temp": event.Temp,
              "Rh":event.Rh
          }
      }).promise();
    } catch (error) {
      throw new Error(`Error in dynamoDB: ${JSON.stringify(error)}`);
    }  
};

answered Apr 5, 2020 at 22:35

PersianIronwood

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1 Comment

Clément Cardonnel Over a year ago

This shorter syntax looks great, but it looks like you're losing the ability to send standard http errors. As seen in this other answer.

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