Get table change notifications from Postgres as JSON

1_triggers.sql

CREATE OR REPLACE FUNCTION table_update_notify() RETURNS trigger AS $$
DECLARE
  id UUID;
BEGIN
  IF TG_OP = 'INSERT' OR TG_OP = 'UPDATE' THEN
    id = NEW.id;
  ELSE
    id = OLD.id;
  END IF;
  PERFORM pg_notify('table_update', json_build_object('table', TG_TABLE_NAME, 'type', TG_OP, 'record', NEW, 'prev', OLD)::text);
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;



DROP TRIGGER users_notify_update ON users;
CREATE TRIGGER users_notify_update AFTER UPDATE ON users FOR EACH ROW EXECUTE PROCEDURE table_update_notify();

DROP TRIGGER users_notify_insert ON users;
CREATE TRIGGER users_notify_insert AFTER INSERT ON users FOR EACH ROW EXECUTE PROCEDURE table_update_notify();

DROP TRIGGER users_notify_delete ON users;
CREATE TRIGGER users_notify_delete AFTER DELETE ON users FOR EACH ROW EXECUTE PROCEDURE table_update_notify();

2_listen_table_update.js

const { Client } = require("pg");

async function main() {
	const pg = new Client("postgres://localhost/authmenow");

	await pg.connect();

	console.log("Connected");

	pg.on("notification", function(msg) {
		console.log("NOTIFICATION", msg);
		if (msg.name === "notification" && msg.channel === "table_update") {
			var pl = JSON.parse(msg.payload);
			console.log("*========*");
			Object.keys(pl).forEach(function(key) {
				console.log(key, pl[key]);
			});
			console.log("-========-");
		}
	});
	pg.query("LISTEN table_update");
}

main().catch(e => {
	console.error(e);
	process.exit(-1);
});