Using promises in a Lambda node for loop - node.js

Question

I'm trying to pre-load a DynamoDB table with records. I have about 1500 records to do. I've tried various ways to loop through only 5 but only one gets entered each time. Here is what I have so far.
'use strict';
var AWS = require('aws-sdk'), documentClient = new AWS.DynamoDB.DocumentClient();
var params = {};
exports.handler = function(event, ctx, callback) {
Promise.all(
event.map(e => {
var params = {
Item: {
UID: ctx.awsRequestId,
AccountName: e.accountname,
AccountStatus: e.accountstatus,
MainNumber: e.mainnumber,
FaxNumber: e.faxnumber,
EmergencyNumber: e.emergencynumber,
EPAPERNO: e.epaperno,
BGB: e.bgb,
WebID: e.webid,
BoxProgram: e.boxprogram,
ReportGroup: e.reportgroup,
CreditLimit: e.creditlimit,
Customer: e.customer,
Transporter: e.transporter,
TSDF: e.tsdf,
Permit: e.permit,
Created: e.created,
Author: e.author,
Modified: e.modified,
Editor: e.editor
},
TableName: 'Accounts'
};
documentClient.put(params, function (err, data){
if(err){
console.log(err);
}else{
console.log(params);
}
});
})
).then(console.log("Done"));
};
Any help would be appreciated.

Answer 1

I recommend using for loop instead of map, Promise.all will call many request by parallel, it maybe take DynamoDB become stressful.
Convert your handler function to async/await function, then just wait until dynamodb process finish.
Ref: Convert aws-sdk callback to Promise
'use strict';
var AWS = require('aws-sdk'), documentClient = new AWS.DynamoDB.DocumentClient();
const insertAccount = async (e) => {
const params = {
Item: {
UID: ctx.awsRequestId,
AccountName: e.accountname,
AccountStatus: e.accountstatus,
MainNumber: e.mainnumber,
FaxNumber: e.faxnumber,
EmergencyNumber: e.emergencynumber,
EPAPERNO: e.epaperno,
BGB: e.bgb,
WebID: e.webid,
BoxProgram: e.boxprogram,
ReportGroup: e.reportgroup,
CreditLimit: e.creditlimit,
Customer: e.customer,
Transporter: e.transporter,
TSDF: e.tsdf,
Permit: e.permit,
Created: e.created,
Author: e.author,
Modified: e.modified,
Editor: e.editor
},
TableName: 'Accounts'
};
return documentClient.put(params).promise(); // convert to Promise
}
exports.handler = async (event, ctx) => { // Async function
for (const item of event) {
console.log(item);
await insertAccount(item) // wait until it finish and go to next item
.catch((error) => {
console.log(error);
// throw error; don't care about this error, just continue
});
}
console.log("Done");
};

Answer 2

Have you tried this :
'use strict';
var AWS = require('aws-sdk'), documentClient = new AWS.DynamoDB.DocumentClient();
exports.handler = async(event, ctx) => {
return Promise.all(
event.map(e => {
var params = {
Item: {
UID: ctx.awsRequestId,
AccountName: e.accountname,
AccountStatus: e.accountstatus,
MainNumber: e.mainnumber,
FaxNumber: e.faxnumber,
EmergencyNumber: e.emergencynumber,
EPAPERNO: e.epaperno,
BGB: e.bgb,
WebID: e.webid,
BoxProgram: e.boxprogram,
ReportGroup: e.reportgroup,
CreditLimit: e.creditlimit,
Customer: e.customer,
Transporter: e.transporter,
TSDF: e.tsdf,
Permit: e.permit,
Created: e.created,
Author: e.author,
Modified: e.modified,
Editor: e.editor
},
TableName: 'Accounts'
};
documentClient.put(params).promise().then(data=>{
console.log(params);
})
})
).then(()=>{
console.log("Done")
}).catch(e=>{
console.log(e)
})
};
Let me know if you find problem with, I haven't it try
Just another idea is using [BatchWriteItem][1] to bulking put process, max 25 per batch