Question

I’m trying to create a registration form with mongoose and MongoDB. I have a unique key, UserId, and every time I create a new entry I would like to take the greatest UserId in the database and increase it by one.
I tried with db.user.find({}).sort({userId: 1}); but it seems not to work.
Thanks

Masiar

Answer 1

What you want to do sounds more like a Schema for Relational Databases with an Auto Increment. I would recommend another solution.

At first you already have a unique id. It get automatically created and are in “_id” field. For me it seems you want to have a UserID for building relation, but you already ca use the value in _id.

The other thing why you want incremented ids could be that you create a webapplication and propably want “nicer” urls? For example. /user/1 instead of /user/abc48df…?

If that is the case i would prefer to create a unique constraint on a username. And instead of an id you use you username in the url “/user/john”.

With this your urls are much nicer. And for building relation you can use _id. And you don’t run into problems with fethcing the highest number first.

To create a unique index:

db.collection.ensureIndex({username: 1}, {unique: true})