express-knex-auto-trx

Express middleware for automatically managing Knex.js database transactions.

Motivation

This middleware will automatically:

• Start a knex database transaction for each inbound request.
• Provide a getTrx() function that can be required by your Express route handlers.
  • Your code can get the current transaction without needing the req object, which is helpful when using data service layers that are decoupled from Express.
• Automatically commit or rollback each transaction based on the HTTP response status code:
  • responses with a 400 or above will rollback
  • all other responses will commit.

How It Works

• Uses cls-hooked to assign a unique transaction to each request
• Uses on-finished to inspect the response statusCode and either commit or rollback the transaction

Usage

Connect the Middleware:

const express = require('express');
const { knexAutoTrx } = require('./middleware/express-knex-auto-trx');
const knex = require('knex')(
  require('knexfile')[process.env.NODE_ENV || 'development']
);

app.use(knexAutoTrx(knex));

Then use the getTrx function as a replacement for the knex object/function:

const { getTrx } = require('../middleware/express-knex-auto-trx');
const express = require('express');
const router = express.Router();

router.post('/users', (req, res, next) => {
  try {
    const [savedUser] = await getTrx() // each request will get its own transaction
      .insert(userData)
      .into('users')
      .returning('*');
    res.status(200).json(savedUser);
  } catch (err) {
    next(err);
  }
});

module.exports = router;