Determine if a record "is new" in the pre save callback

Is there a way to find out if a record "is new" (has not been save yet) in the pre save callback of mongoose model schema?

Yes, there's an isNew boolean property on a model instance that indicates that. Access it as this.isNew from your pre save middleware.

var MySchema = new Schema({...});

MySchema.pre('save', function(next) {
    if (this.isNew) {
        // Hooray!
        next()
    }
});