Node js, using mongoose with Q promise does not call reject function

Question

I have started learning promises and I wanted use it with mongoose. I have read that mongoose promises are primitive so I have applied to q by using this code:

var mongoose = require('mongoose');
var q = require('q');
mongoose.Promise = q.Promise;

The I have created my schema and model and try to call functions via promises:

User.findOne({chat_id: 2}).exec().then(
    function (obj) {
        console.log("SUCCESS");
        console.log(obj);
    },
    function (err) {
        console.log("ERROR");
        console.log(err);
    }

).done();

When I call this code it always calls resolve part and skips reject part. My console shows always function which has SUCCESS line even if I intentionally query for not existing data .

Am I missing something, or mongoose will always use Model.method().exec().then(resolveFunction) ?

Answer 1

Not finding something is not an error, it just means you did not find something. See: What is returned from Mongoose query that finds no matches? and likely your problem is related to this Mongoose JS findOne always returns null

Also try this: Note I have not worked with q.Promise, I use bluebird.

  User.findOne({chat_id: 2}).exec().then(
    function (obj) {
      if (obj.chart_id === 2) {
        console.log("SUCCESS");
        console.log(obj);
      } else {
        console.log("obj with obj.chart_id == 2 NOT FOUND");
        console.log(obj);
      }

    },
    function (err) {
      console.log("ERROR");
      console.log(err);
    }

  ).done();