Create Multiple Trustlines Upon Account Creation

Question

This code successfully creates a new account, and funds it with 5 XLM, but it does not add trust lines to the account. Is it acceptable to chain a changeTrust operation within this transaction? Or do I need to construct a separate change trust operation, signed by the new account?

This also does not write to firebase. Any idea why?

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp();

const StellarSdk = require('stellar-sdk');
StellarSdk.Network.useTestNetwork();
var server = new StellarSdk.Server('https://horizon-testnet.stellar.org');

var publicKey = 'xxx';
var secretKey = 'xxx';
var sourceKeyPair = StellarSdk.Keypair.fromSecret(secretKey);
var issuerPublicKey = 'xxx';

exports.createAccount = functions.https.onCall((data, context) => {

    var newPublicKey = data.publicKey;

    server.loadAccount(publicKey)
    .then(function(source) {

      var transaction = new StellarSdk.TransactionBuilder(source)

      .addOperation(StellarSdk.Operation.createAccount({
        destination: newPublicKey,
        startingBalance: '5',
      }))
      .addOperation(StellarSdk.Operation.changeTrust({ 
        asset: new StellarSdk.Asset('USD', issuerPublicKey),
      }))
      .addOperation(StellarSdk.Operation.changeTrust({
        asset: new StellarSdk.Asset('GOLD', issuerPublicKey),
      }))
      .setTimeout(StellarSdk.TimeoutInfinite)
      .build();

    transaction.sign(sourceKeyPair);

    server.submitTransaction(transaction)
        .then(function(transactionResult) {
            console.log(JSON.stringify(transactionResult, null, 2));
            admin.firestore().collection('users').doc(newPublicKey).set({
                publicKey: newPublicKey,
            })
        })
        .catch(function(err) {
            console.log('An error has occured:');
            console.log(err);
          });
    })
    .catch(function(err) {
        console.error(err);
    })

})

Answer 1

You have to specify the affected new account, otherwise all operations within a transaction refer to the account that creates the transaction (sourceKeyPair in your case).

.addOperation(StellarSdk.Operation.changeTrust({
              asset: asset,
              source: newPublicKey
          }))