Mongoose.js transactions

Question

I know MongoDB doesn\'t support transactions as relational databases do, but I still wonder how to achieve atomicity for several operations. Hunting around the web, I see people

Answer 1

You can simulate a transaction by manually rolling-back the changes whenever an error occurs. In your above example, simply remove the saved document if the other one fails.

You can do this easily using Async:

    function rollback (doc, cb) {
      doc.remove(cb);
    }

    async.parallel([
          player.save.bind(player),
          story.save.bind(story),
      ],
      function (err, results) {
        if (err) {
          async.each(results, rollback, function () {
            console.log('Rollback done.');
          });
        } else {
          console.log('Done.');
        }
      });

Obviously, the rollback itself could fail -- if this is a not acceptable, you probably need to restructure your data or choose a different database.

Note: I discussed this in detail on this post.