express-knex-transaction-middleware.ts

README.md

Middleware factory for using a single transaction per request. Transactions are only started if a downstream handler requests one. If a transaction is started by the handler, it is automatically committed or rolled back once the handler completes.

Usage:

Enable the middleware:

app.use(makeDatabaseTransactionMiddleware(knex));

In handler:

async function handleRequest(req, res) {
 const transaction = req.getTransaction();
 // Potentially failing logic here
}

middleware.ts

import type { Knex } from 'knex';

function makeDatabaseTransactionMiddleware(knex: Knex) {
  async function databaseTransactionMiddleware(req, res, next) {
    let transaction;

    function getTransaction() {
      if (!transaction) {
        transaction = knex.transaction();
      }
      return transaction;
    }

    try {
      req.getTransaction = getTransaction;
      await next();
      if (transaction) {
        await transaction.commit();
      }
    } catch {
      if (transaction) {
        await transaction.rollback();
      }
    }
  }
  return databaseTransactionMiddleware;
}