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  • Express with Async/Await

My preferred way to use node-postgres (and all async code in node.js) is with async/await. I find it makes reasoning about control-flow easier and allows me to write more concise and maintainable code.

This is how I typically structure express web-applications with node-postgres to use async/await:

- app.js
- index.js
- routes/
  - index.js
  - photos.js
  - user.js
- db/
  - index.js <--- this is where I put data access code

That's the same structure I used in the project structure example.

My db/index.js file usually starts out like this:

const { Pool } = require('pg')
 
const pool = new Pool()
 
module.exports = {
  query: (text, params) => pool.query(text, params),
}

Then I will install express-promise-router and use it to define my routes. Here is my routes/user.js file:

const Router = require('express-promise-router')
 
const db = require('../db')
 
// create a new express-promise-router
// this has the same API as the normal express router except
// it allows you to use async functions as route handlers
const router = new Router()
 
// export our router to be mounted by the parent application
module.exports = router
 
router.get('/:id', async (req, res) => {
  const { id } = req.params
  const { rows } = await db.query('SELECT * FROM users WHERE id = $1', [id])
  res.send(rows[0])
})

Then in my routes/index.js file I'll have something like this which mounts each individual router into the main application:

// ./routes/index.js
const users = require('./user')
const photos = require('./photos')
 
module.exports = (app) => {
  app.use('/users', users)
  app.use('/photos', photos)
  // etc..
}

And finally in my app.js file where I bootstrap express I will have my routes/index.js file mount all my routes. The routes know they're using async functions but because of express-promise-router the main express app doesn't know and doesn't care!

// ./app.js
const express = require('express')
const mountRoutes = require('./routes')
 
const app = express()
mountRoutes(app)
 
// ... more express setup stuff can follow

Now you've got async/await, node-postgres, and express all working together!

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