Cannot read property of "amount" from the request body

Question

I am building REST APIs in Nodejs using AWS. I am expecting a response on Postman saying that the "

Your Bid Must Be Higher than ${auction.highestBid.amount}

" But instead, I get an Internal Server Error on Postman and the error on AWS Cloudwatch looks like: enter image description here . However, I am sending a request on Postman as: enter image description here Please help!!

I am Expecting the response as: Your bid must be higher than

${auction.highestBid.amount} 

The patch request body looks like: enter image description here While the create Request looks like: enter image description here

//placeBid.js

 const AWS = require('aws-sdk'); const createError = require('http-errors'); const {getAuctionById} = require('./getAuction'); const dynamodb = new AWS.DynamoDB.DocumentClient(); async function placeBid(req) { const { id } = req.pathParameters; const { amount } = JSON.parse(req.body); const auction = getAuctionById(id); if(amount <= auction.highestBid.amount) throw new createError.Forbidden(`Your Bid Must Be Higher than ${auction.highestBid.amount}`); const params = { TableName: 'AuctionsTable', Key: {id}, UpdateExpression: 'set highestBid.amount =:amount', ExpressionAttributeValues: { ':amount': amount }, ReturnValues: 'ALL_NEW' } let updatedAuction; try { const result = await dynamodb.update(params).promise(); updatedAuction = result.Attributes; } catch (error) { console.error(error); throw new createError.InternalServerError(error); } return{ statusCode: 200, body: JSON.stringify(updatedAuction) } } module.exports.handler = placeBid;

//getAuction.js

const AWS = require('aws-sdk');
    const createError = require('http-errors');
    
    const dynamodb = new AWS.DynamoDB.DocumentClient();
    
    module.exports.getAuctionById = async(id) => {
      let auction;
      try {
        const result = await dynamodb.get({
          TableName : 'AuctionsTable',
          Key : {id}
        }).promise()
        auction = result.Item;
    
      } catch (error) {
        console.error(error);
        throw new createError.InternalServerError(error);
      }
      if(!auction){
        throw new createError.NotFound(`Auction with ID ${id} not found`);
      }
      return auction;
    }
    
    async function getAuction(req) {
      const { id } = req.pathParameters;
      const auction = await getAuctionById(id);
      return{
        statusCode : 200,
        body : JSON.stringify(auction)
      }
    }
    
    module.exports.handler = getAuction

Answer 1

getAuctionById is async . It returns a Promise . You have to await it before using its value:

const auction = await getAuctionById(id);

Answer 2

You're throwing an error without catching it throw new createError.Forbidden(`Your Bid Must Be Higher than ${auction.highestBid.amount}`);, so your Lambda crashes and returns 500 error. That's expected behavior.

Just return a valid response instead

return {
    statusCode : 400,
    body : `Your Bid Must Be Higher than ${auction.highestBid.amount}`
  }

Answer 3

If you want to see an example of writing a REST API that uses the AWS SDK for JavaScript (v3 ) that can invoke AWS Services and return data, see this example in the AWS Code Catelog . Once you successfully build the REST API, you can use Postman to sent requests and view the responses.

This example performs these tasks:

• Integrate a React.js web application with AWS services.The React app uses the Rest API (you can also use Postman to view the responses)
• List, add, and update items in an Aurora table.
• Send an email report of filtered work items by using Amazon SES.
• Deploy and manage example resources with the included AWS CloudFormation script.

https://docs.aws.amazon.com/code-library/latest/ug/aurora_example_cross_RDSDataTracker_section.html