Saving populated values in Mongoose
Instead of using depopulate() method of mongoose, you can use underscore library of node, which provides a function pick and returns the opted values from given object and computes result faster here is example!
app.get('/post/:id', function (req, res, next) {Post.findById(req.params.id).populate('likes').exec(function (err, post) {if (err) return next(err); var depopulate = _.pick(post, '_id'); res.json(depopulate);});});depopulate variable will store _id's from resulted queried document and you can easily send all _id's to client.
I know this question was posted 2 years ago, but i thought that it might help you..You can override some pre-defined methods to get done what you need.
UserSchema.methods.toJSON = function () { var user = this.toObject(); return _.pick(user, ['_id', 'email']);};Like i have overridden toJSON method to send only _id and email instead of sending whole user doc back.