PoC implementation of server side transactions

Implementation is based on using Meteor.EnvironmentVariable to store the MongoDB session and overrides in MongoInternals.NpmModule.Collection for each method that supports sessions.

Usage

// server-side
import {runInTransaction} from 'meteor/equium:mongo-transactions';

const Invoice = new Mongo.Collection('invoice');
const LineItems = new Mongo.Collection('lineItems');
const Payments = new Mongo.Collection('payments');

function (invoice, lineItems) {
    runInTransaction(() => {
        Invoice.insert(invoice);
        LineItems.insert(lineItems);

        const payment = createPaymentDoc(); 
        Payments.insert(payment);
    });
}

Exported methods/variables

runInTransaction<R>(fn: () => R, options?: RunInTransactionOptions): R;

fn - method to be run in transaction

options - optional SessionOptions, https://mongodb.github.io/node-mongodb-native/3.6/api/global.html#SessionOptions

isInTransaction(): boolean;

Whether we already are in the transaction.

sessionVariable: Meteor.EnvironmentVariable

This is the actual Meteor.EnvironmentVariable instance used by the package. You could get MongoDB's ClientSession instance with sessionVariable.get().

It will return undefined if there is no session.

Testing

cd test-app
meteor npm i
# using browser driver
TEST_BROWSER_DRIVER=puppeteer MONGO_URL= ROOT_URL=  meteor test-packages --port=3000 --driver-package meteortesting:mocha ../