Mongoose return value from withTransaction callback

Question

I want to utilize mongoose's withTransaction helper particularly for its ability to automatically retry transient transaction errors. However, it seems that the withTransaction helper is incapable of returning data, which is a problem for me.

I have code that looks like:

import { startSession } from 'mongoose';

async addItem(itemData) {
    const session = await startSession();
 
    session.startTransaction();
    try {
        const item = await new Item({ itemData }).save({ session });
        
        // a bunch of other async operations...

       await session.commitTransaction();
       session.endSession();

       return item;
    } catch (error) {
        await session.abortTransaction();
        session.endSession();
        throw error;
    }
}

How can I either (1) use the withTransaction helper but still have this function returning the item as it currently does, or (2) make this function automatically retry on transient transaction errors through some way other than using withTransaction.

Answer 1

This appears to be a known issue in the node driver. Some workarounds are provided in that ticket.

Answer 2

I wrote a simple helper that internally uses withTransaction to solve the problem and make transactions less verbose with mongoose.

After installing mongoose-trx you can simply do:

const transaction = require('mongoose-trx');

const [customer] = await transaction(session => Customer.create([{ name: 'Test' }], { session }));

// do whatever you need to do with the customer then return it

It supports transaction options as well, see the documentation on how to do it.