Getting Cognito User and Group inside Amplify AWS API function

Question

I used Amplify Cli to create the templated api 'amplify add api' with new lambda function and cognito authentication. This is the code generated in the index.js file of the lambda function:

/************************************
 index.js 
*************************************/
const awsServerlessExpress = require('aws-serverless-express');
const app = require('./app');

const server = awsServerlessExpress.createServer(app);

exports.handler = (event, context) => {
console.log(`EVENT: ${JSON.stringify(event)}`);
awsServerlessExpress.proxy(server, event, context);
};

/************************************
 HTTP put method for insert object in app.js
*************************************/

app.put(path, function(req, res) {

if (userIdPresent) {
req.body['userId'] = req.apiGateway.event.requestContext.identity.cognitoIdentityId || UNAUTH;
} else {
// Get the unique ID given by cognito for this user, it is passed to lambda as part of a large string in event.requestContext.identity.cognitoAuthenticationProvider
let userSub = req.apiGateway.event.requestContext.identity.cognitoAuthenticationProvider.split(':CognitoSignIn:')[1];
let requestIp = req.apiGateway.event.requestContext.identity.sourceIp;
let userPoolId = process.env.AUTH_TDOCWEBAPP001_USERPOOLID;
let request = {
UserPoolId: userPoolId, // Set your cognito user pool id
AttributesToGet: [
'email',
'given_name',
'family_name',
],
Filter: 'sub = "' + userSub + '"',
Limit: 1
}
//let users = await cognitoClient.listUsers(request).promise(); //Doesn't work because await not allowed
let users = cognitoClient.listUsers(request);
console.log("got user in put:", users[0]);
// TODO: Get the group that the user belongs to with "cognito:grouops"?

// Set userId and sortKey
req.body['userId'] = users[0].sub;
req.body['sortKey'] = sortKeyValue;
req.body['updatedByIp'] = requestIp;
req.body['createdAt'] = new Date().toISOString(); //ISO 8601 suppored by DynamoDB
req.body['updatedAt'] = new Date().toISOString();
req.body['isDeleted'] = false;

}

let putItemParams = {
TableName: tableName,
Item: req.body
}
dynamodb.put(putItemParams, (err, data) => {
if(err) {
res.statusCode = 500;
res.json({error: err, url: req.url, body: req.body});
} else{
res.json({success: 'put call succeed!', url: req.url, data: data})
}
});
});

So right now, when I call the lambda via the API, i get users is undefined. I'm trying to get the user object and then the groups that it belongs. Not sure how to do it if the function doesn't allow async... Please help

Answer 1

I found it myself the solution.

let users = await cognitoClient.listUsers(request);

or

let users = cognitoClient.listUsers(request, function(err, data) {...});

I needed wait to get users from the Cognito.