Javascript 'then' not working as expected in Ripple-lib calls

Question

I'm trying to create a simple example of payments over the XRPL using Ripple-lib. The idea is to send several payments to different accounts stored in an array. I've made it kind of work in a different way as it is expected, but when using the 'then' method (as the docs recommend) does not work at all.

I'm a total newbie to Javascript so I don't have a good grasp on the language nor asyncronous coding and promises. When using the 'then' paradigm, the code stops working and no output can be seen in the console. This is the code I'm currently using. In the comments inside the 'SendXRP' function I explain the problem. How can this be re-arranged? Between the two ways, what is the proper one to code it?

'use strict';
const RippleAPI = require('ripple-lib').RippleAPI;

const sender = 'r*********************************';
const secret = 's****************************';
const destinations = ['r*********************************',
                      'r*********************************',
                      'r*********************************'];
const amount = 5;

// Instantiate Ripple API
const api = new RippleAPI({
  server: "wss://s.altnet.rippletest.net:51233"
});

run();


async function sendXRP(amount, fee, destination, memo) {

  // Update amount
  amount = (amount - fee).toString();

  // Build payment
  const payment = {
    source: {
      address: sender,
      maxAmount: {
        value: amount,
        currency: 'XRP'
      }
    },
    destination: {
      address: destination,
      amount: {
        value: amount,
        currency: 'XRP'
      }
    },
    memos: [
      {
          data: memo
      }
    ]
  };

  // Build instuctions
  const instructions = {
    maxLedgerVersionOffset: 5
  };

  console.log('Sending ' + amount + ' to ' + destination);

  // THIS KIND OF WORKS FOR NOW
  // Prepare the payment
  const preparedTX = await api.preparePayment(sender, payment, instructions);

  // Sign the payment
  const signedTX = api.sign(preparedTX.txJSON, secret);

  // Submit the payment
  const result = await api.submit(signedTX['signedTransaction']);

  // Return TX hash on successful TX
  if ('resultCode' in result && result['resultCode'] == 'tesSUCCESS') {
      return signedTX.id;
  } else {
      return null;
  }

  // THIS IS MORE SIMILAR TO HOW IT IS DONE IN THE DOCS! NOT WORKING!
  // ALSO, HOW DO I RETURN THE RESULT OF API.SIGN TO THE MAIN FUNCTION?
  // Prepare the payment
  // api.preparePayment(sender, payment, instructions).then(preparedTX => {
  //     // Sign the payment
  //     api.sign(preparedTX.txJSON, secret).then(signedTX => {
  //     // Submit the payment
  //     api.submit(signedTX['signedTransaction']);
  //     })
  // }).catch(console.error);
}

function run() {
// Connect to Ripple server
api.connect().then(() => {
  return api.getFee();
}).then(async fee => {

  for (var i in destinations) {
    var hash = await sendXRP(amount, Number(fee), destinations[i], 'memotext');
    console.log(hash);
  }

}).then(() => {
  return api.disconnect();
}).catch(console.error);
}

`async/await` is much nicer to code than the `then` soup. You can’t return anything to the main function when using promises. You have to do something with the final result in the last `then`. — Strelok, Oct 18 '18 at 15:37
If the docs say that the `sign` method returns a promise (which the commented out code suggests), then you should use `await` in your code when calling it. — trincot, Oct 18 '18 at 15:37

mikeemay · Answer 1 · 2019-04-02T14:24:43.900

Could it be that some of the transactions failed to send? If it failed, the result variable from sendXRP should have the txresult, but since you returned null if the result code is not tesSUCCESS, it doesn't return the result information.

const result = await api.submit(signedTX['signedTransaction']);

if ('resultCode' in result && result['resultCode'] == 'tesSUCCESS') {
  return signedTX.id;
} else {
  return null;
}

Before, when I tried submitting transactions consecutively, it would fail and return error code tefPAST_SEQ.

"The sequence number of the transaction is lower than the current sequence number of the account sending the transaction." from https://developers.ripple.com/tef-codes.html

I recommend removing the if('resultCode' in result...) block and check the transaction result. If the transactions failed with tefPAST_SEQ error, my solution to this is set the account sequence in instructions manually or add setTimeOut after each submit.

Javascript 'then' not working as expected in Ripple-lib calls

1 Answers1