Cloud Function that gets document data, posts to PubSub Topic with a Schema and deletes the document

index.js

const { Logging } = require('@google-cloud/logging');
const logging = new Logging();
const log = logging.log('publishToBigQuery');

const { PubSub } = require('@google-cloud/pubsub');
const pubsub = new PubSub();

const protobuf = require('protobufjs');

const Firestore = require('@google-cloud/firestore');
const firestore = new Firestore();

exports.publishToBigQuery = async (event, context) => {
    const affectedDoc = firestore.doc(`messages/${context.params.documentId}`);

    try {
        const documentSnapshot = await affectedDoc.get();
        if (documentSnapshot.exists) {
            const firestoreData = documentSnapshot.data();

            const topic = pubsub.topic('firestore-to-BQ');

            const schema = pubsub.schema('message');
            const info = await schema.get();

            const type = protobuf.parse(info.definition, { keepCase: true });
            const ProtocolBuffer = type.root.lookupType('ProtocolBuffer');
            const message = ProtocolBuffer.create(firestoreData);

            const data = Buffer.from(JSON.stringify(message.toJSON()));
            const value = await topic.publishMessage({data});
            log.info(log.entry(`Document published on pubsub ${value}`));

            const delResult = await affectedDoc.delete();
            log.info(log.entry(`Document deleted. ${delResult}`));
        } else {
            log.info(log.entry(`Document doesn't exist. ${JSON.stringify(affectedDoc)}`));
        }
    } catch (error) {
        log.error(log.entry(`Error when fetching document: ${error}`));
    };
};