mongoose insert data with promise - node.js

Question

My goal is to insert a new country (with incremented country_id) into the db if it doesn't exist. In that case I try to get the max country_id and insert a new country with country_id + 1. Otherwise I don't do anything.
readFile is a promise to readfile,
filetoArray changes that file content to an array,
processMap processes each array element and decide if we store the info to mongodb or not
The problem is:
promise.promisifyAll(Country.findOne({}).sort({'zid' : -1}).exec()
always gives me the same result even when some data are already inserted into the database...
Any suggestions are greatly appreciated. Thanks.
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var CountrySchema = new Schema({
zn: {type: String, required: true},
zid: {type: Number, required: true}
});
var promise = require('bluebird');
function processMap(data){
return promise.bind(data).then(insertCountry);
}
var insertCountry = function() {
var googledata = this; // from bind promise
return promise.promisifyAll(Country.findOne({zn: googledata.country}).exec())
.then(function(dbdata){ return {dbdata: dbdata, googledata: googledata}; })
.then(insertCountryIfNotExist)
}
var insertCountryIfNotExist = function(data){
return promise.promisifyAll(Country.findOne({}).sort({'zid' : -1}).exec())
.then(function(d){
var newc = new Country({zn: data.googledata.country, zid: d.zid + 1});
return promise.promisifyAll(newc.saveAsync())
});
}
// main code is here
readFile(file)
.then(filetoArray)
.map(processMap, {concurrency: 1}) // end of then
.then(function(data){
console.log('done');
})

Answer 1

Actually Exec returns a promise inherited from mpromise, there's no need to use bluebird on your case or if you want to use bluebird, then don't mix the mongoose promises with blue bird.
some example:
var insertCountry = function() {
var googledata = this;
return Country.findOne({zn: googledata.country}).exec()
.then(function(dbdata){
return {dbdata: dbdata, googledata: googledata};
})
.then(function(data){
return Country.findOne({}).sort({'zid' : -1}).exec()
.then(function(d){
var newc = new Country({zn: data.googledata.country, zid: d.zid + 1});
return newc.save();
})
})
}