Artur Chmaro

blog about web technologies

PostgreSQL/Sequelize / NodeJS - Updating records

One of my applications is aggregating sports matches. I want to update a status of all matches that have empty status and started 20 minutes ago. Using Rails ActiveRecord it is as simple as:

Match.where('status = ? AND starts_at < ?', '', - 20.minutes)
     .update_all(status: 'Canceled')

As I'm learning NodeJS I decided to write a script that will do the exactly same thing but in NodeJS. First I've initialized project:

$ npm init

Then installed sequelize (nice promise-based ORM) and pg packages:

$ npm install sequelize --save
$ npm install pg --save

Before we can query our PostgreSQL we need to establish a connection to it and define models we want to use. I've created db.js file for it:

const Sequelize = require('sequelize');
const sequelize = new Sequelize('postgres://dbuser:dbpasss@localhost:5432/app_db');

const Match = sequelize.define('match', {
    starts_at: {
      type: Sequelize.DATE
    status: {
      type: Sequelize.STRING
    timestamps: true, createdAt: 'created_at', updatedAt: 'updated_at'

module.exports.sequelize = sequelize;
module.exports.Match = Match;

Now let's create cancelMatches() function in the separate file and export it:

const twentyMinsAgo = new Date( - 1000 * 60 * 20);

module.exports = function cancelMatches(db) {
    return new Promise((resolve, reject) => {
        db.Match.update({status: 'Canceled'}, {where: {status: '', starts_at: {$lt: twentyMinsAgo}}})
            .then(function(result) {

We have DB connection, model and function to do the job. Let's combine all those things at index.js file:

const db = require('./db.js');
const cancelMatches = require('./cancelMatches');


Done! Now we can fire this script every time we want (manually or using cron):

$ node ./index.js