Mongoose.js: how to implement create or update?

I have a request which body contains data and _id

What is the better way to implement code that will update if record with _id exists and will create one is there is no one? My code:

var obj = req.body;
Model.findById(obj._id, function(err, data){
    if (!data){
        var model = new Model(obj)
        model.save(function(err, data){
            res.send({method: 'create', error: err, data: data})
        })
    } else {
        Model.findByIdAndUpdate(obj._id, obj, function(){
            res.send({method: 'update', error: err, data: data})
        })
    }

I'm just thinking maybe there is beter way of doing this.

You can do that with a single upsert:

var obj = req.body;
var id = obj._id;
delete obj._id;
if (id) {
    Model.update({_id: id}, obj, {upsert: true}, function (err) {...});
}

The caveat is that your model's defaults and middleware (if any) will not be applied.

Mongoose 4.x Update

You can now use the setDefaultOnInsert option to also apply defaults if the upsert creates a new document.

Model.update({_id: id}, obj, {upsert: true, setDefaultsOnInsert: true}, cb);