MongoDB and NodeJS write array of objects from mongodb to a json file

Question

I need to write an array of places to a JSON file, I take the places from the MongoDB. The code below work

'use strict';
const jsonfile = require('jsonfile');
const debug = require('debug')('myproject:server');
const Place = require('../models/place.js');
const path = './public/places.json';


Place.find({
    reviewed: true
  }, (err, places) => {
    if (err) {
      debug(err);
    } else {
      jsonfile.writeFile(path, places, (err) => {
        if (err) {
          debug(err);
        }
      });
    }
  });

This is what a single object in the JSON file looks like

{ _id: 58b8d11cbaa41f288236d5fa,
  __v: 0,
  mainImg: 'placeImg-1490464803517.jpg',
  reviewed: true,
  date: 2017-03-03T02:12:44.313Z,
  description: 'Lorem ipsum dolor sit amet, consectetur adipisicing elit. Eum illo odit animi architecto.',
  coord: { lng: 2.166948616504669, lat: 41.382971076851476 },
  type: 'museum',
  title: 'Lorem' }

Since I have a lot of objects in the array places it makes sense to remove the properties that are not used on the client side, such as __v and reviewed

I tried doing following before writing array to the file

let shorterPlaces = [];
places.forEach((el, i) => {
  delete el['__v'];
  delete el['reviewed'];
  shorterPlaces.push(el);
});

and then writing shorterPlaces to a file, but the properties remained.

When I tried logging out the object keys inside the for each loop with console.log(Object.keys(el)); I got [ '$__', 'isNew', 'errors', '_doc' ] which does not make any sense to me. Is there something that I am missing here or unaware of?

The code that deletes properties looks fine to me, can you show how you used this modification? — Maria Ines Parnisari
– Maria Ines Parnisari, Commented May 21, 2017 at 19:28
You can use projection to remove the fields from the response. Something like Place.find({ reviewed: true }, '-__v -reviewed', (err, places) .... — s7vr
– s7vr, Commented May 22, 2017 at 0:39
@MariaInesParnisari the properties are not removed with delete — Anton Kastritskiy
– Anton Kastritskiy, Commented May 22, 2017 at 11:11
@Veeram can you please post your comment as an answer so I can mark it as correct? — Anton Kastritskiy
– Anton Kastritskiy, Commented May 22, 2017 at 11:11
Possible duplicate of Mongoose, find, return specific properties — s7vr
– s7vr, Commented May 22, 2017 at 11:47

richsilv · Accepted Answer · 2017-05-21 21:00:13Z

2

Based on the file you're requireing it looks like you're using Mongoose. Mongoose collection's find method returns Mongoose documents, which are objects with their own methods and getters/setters, rather than just the plain data in the database.

If you want just the data in a regular JS object, you need to use lean:

Place.find({ reviewed: true })
  .lean()
  .exec((err, places) => {
     // Here, places will be an array of plain objects that you can
     // manipulate as normal
   })

answered May 21, 2017 at 21:00

richsilv

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