CODEWITHSUNDEEP
node.jsmongodbmongoose
Marv
Marv

Reputation: 758

Mongoose update document in the moment of finding it

I am developing a query of tasks. When a task is requested, I am returning the oldest one with the following code:

Task.find({})
        // Filter for those that are not started yet
        .where('startDate').equals(null)
        // Sort ascending to get the oldest
        .sort({ reqDate: 'asc' }).findOne(function (err, task) { ... }

Inside of the final brackets, I set the startDate to the current time. The requests are done by calling a single NodeJS (Express) API running express and communicating with MongoDB by using Mongoose.

This works well with just one person requesting tasks, but I am thinking of a huge scale right now. What if there are multiple people requesting in the same moment, all receiving the same task as they come in in the same timespan of a few milliseconds?

Is there a way to make sure that the startDate of the document is set in the moment it is found by mongoose?

Upvotes: 0

Views: 174

Answers (1)

rsp
rsp

Reputation: 111278

In Mongo there's db.collection.findAndModify() and db.collection.findOneAndUpdate():

But you are likely to get race conditions anyway. You may be better off implementing your queues with Redis, RabbitMQ, ZeroMQ, ActiveMQ, NSQ etc.

See:

Much more tools are here:

To sum it up, you may be able to work around your current problem with db.collection.findAndModify() and db.collection.findOneAndUpdate() but using a proper tool for queues or pub/sub will save you a lot of trouble, especially when you start processing multiple tasks concurrently.

Upvotes: 2

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