Making mongoose queries work with bluebird's reflect

Question

I am trying to use Bluebird with mongoose. Here is my implementation.

const Bluebird = require('bluebird');
const mongoose = require('mongoose');
const Entity = require('./entity');
mongoose.Promise = Bluebird;

Now I try to do something like this.

let promises = [];
promises.push(Entity.findOne({ country: 'HONGKONG' }));
promises.push(Entity.findOne({ country: 'INDIA' }));
promises.push(Entity.findOne({ country: 'THAILAND' }));

I know the above query doesn't make sense. It's just an example for multiple promise.

Now I try to implement Bluebirds reflect

return Bluebird.all(promises.map(function (promise) {
  return promise.reflect();
}))
  .then(response => {
    console.log(response.filter(r => r.isFulfilled() ));
    console.log(response.filter(r => !r.isFulfilled() ));
  }).catch(err=>{
    console.log(err);
  })

I get error promise.reflect is not a function

But, When I do this, It works fine.

promises.push(new  Bluebird( (resolve, reject) => resolve(Entity.findOne({ country: 'HONGKONG' } )) ));
promises.push(new  Bluebird( (resolve, reject) => resolve(Entity.findOne({ country: 'INDIA' } )) ));
promises.push(new  Bluebird( (resolve, reject) =>  resolve(Entity.findOne({ country: 'THAILAND' } )) )); 

My question is, Why mongoose is not taking bluebird's promise implementation normally. Do I need to explicitly resolve each query with Bluebird?

Answer 1

I think it fails because .findOne() does not return a Promise, but a Query Object. You have to add .exec() at the end.

Try:

let promises = [];
promises.push(Entity.findOne({ country: 'HONGKONG' }).exec());
promises.push(Entity.findOne({ country: 'INDIA' }).exec());
promises.push(Entity.findOne({ country: 'THAILAND' }).exec());

Here you have more information about Promises in Mongoose. Why you need to use the .exec() function is explained as well.