node.js - Increment counter with Cloud Functions for Firebase

Question

I have seen an increment counter with Cloud Functions referencing Realtime Database, but not Firebase Firestore yet.

I have a cloud function that listens for new documents:

exports.addToChainCount = functions.firestore
    .document('chains/{name}')
    .onCreate((snap, context) => {

    // Initialize document
    var chainCounterRef = db.collection('counters').doc('chains');

    var transaction = db.runTransaction(t => {
        return t.get(chainCounterRef).then(doc => {
            // Add to the chain count
            var newCount = doc.data().count + 1;
            t.update(chainCounterRef, { count: newCount });
        });
    }).then(result => {
        console.log('Transaction success!');
    }).catch(err => {
        console.log('Transaction failure:', err);
    });
    return true;
});

I'm attempting the above transaction, but when I run firebase deploy in terminal I get this error:

error Each then() should return a value or throw promise/always-return functions predeploy error: Command terminated with non-zero exit code1

This is my first attempt at anything node.js, and I'm not sure I've written this right.

Answer 1

Waitting for answers