withTransaction

The more perfect variant of the native driver's withTransaction function.

withTransaction(callback) => Promise

withTransaction(callback) => Promise

import { withTransaction, getCollection } from 'mongodash';
import { ClientSession } from 'mongodb';

const createdDocuments = await withTransaction(async (session: ClientSession) => {
    const collection = getCollection('myCollection');
    const myDocument1 = { value: 1 };
    const myDocument2 = { value: 2 };
    
    await collection.insertOne(myDocument1, { session });
    await collection.insertOne(myDocument2, { session });
    
    return [myDocument1, myDocument2];
});

Benefits over the native driver's function

Benefits over the native driver's withTransaction function:

• automatically starts a new clientSession
• automatically ends the clientSession (even on failure)
• propagates the value returned from the callback

It does all the necessary code described in the official docs automatically.

Post Commit Hooks

You can register hooks that will be executed only after the transaction successfully commits.

registerPostCommitHook(session, callback) => void

registerPostCommitHook(session: ClientSession, callback: () => void | Promise<void>) => void

This is extremely useful for side effects that should happen effectively "outside" the transaction but only if the transaction succeeds, such as:

• Sending emails
• invalidating caches
• Triggering webhooks

import { withTransaction, registerPostCommitHook } from 'mongodash';

await withTransaction(async (session) => {
    // 1. Modify DB inside transaction
    await db.collection('orders').insertOne({ status: 'created' }, { session });
    
    // 2. Register side-effect
    registerPostCommitHook(session, async () => {
        // This runs ONLY if transaction commits successfully
        await emailService.sendOrderConfirmation();
    });
});