Mongoose save() using native promise - how to catch errors

Question

I am trying to catch errors thrown from Mongoose using Mongoose's native promises. But I don't know where to get the error object from Mongoose.

I would like the errors to be thrown in the .then()s and caught in .catch() if possible.

var contact = new aircraftContactModel(postVars.contact);
contact.save().then(function(){
    var aircraft = new aircraftModel(postVars.aircraft);
    return aircraft.save();
})
.then(function(){
    console.log('aircraft saved')
}).catch(function(){
    // want to handle errors here
});

Trying not to use another library, as .save() returns a promise natively.

Answer 1

MongooseJS uses the mpromise library which doesn't have a catch() method. To catch errors you can use the second parameter for then().

var contact = new aircraftContactModel(postVars.contact);
contact.save().then(function() {
    var aircraft = new aircraftModel(postVars.aircraft);
    return aircraft.save();
  })
  .then(function() {
    console.log('aircraft saved')
  }, function(err) {
    // want to handle errors here
  });

UPDATE 1: As of 4.1.0, MongooseJS now allows the specification of which promise implementation to use:

Yup require('mongoose').Promise = global.Promise will make mongoose use native promises. You should be able to use any ES6 promise constructor though, but right now we only test with native, bluebird, and Q

UPDATE 2: If you use mpromise in recent versions of 4.x you will get this deprication warning:

DeprecationWarning: Mongoose: mpromise (mongoose's default promise library) is deprecated