habitica/migrations/archive/2015/20150906_groups_fix_leaders.js

/*
 * Make sure leaders are existing users
 */

let mongo = require('mongoskin');
let async = require('async');

let dbserver = 'url';
let dbname = 'dbname';
let countGroups = 0;
let countUsers = 0;

let db = mongo.db(`${dbserver  }/${  dbname  }?auto_reconnect`);
let dbUsers = db.collection('users');
let dbGroups = db.collection('groups');

console.log('Begins work on db');

function findGroups (gt) {
  let query = {};
  if (gt) query._id = {$gt: gt};

  console.log(query);

  dbGroups.find(query, {
    fields: {_id: 1, members: 1, leader: 1},
    limit: 10000,
    sort: {
      _id: 1,
    },
  }).toArray(function (err, groups) {
    if (err) throw err;

    let lastGroup = null;
    if (groups.length === 10000) {
      lastGroup = groups[groups.length - 1];
    }

    async.eachLimit(groups, 30, function (group, cb1) {
      countGroups++;
      console.log('Group: ', countGroups, group._id);

      let members = group.members;

      dbUsers.findOne({_id: group.leader}, {fields: {_id: 1}}, function (err, user) {
        if (err) return cb1(err);

        // If leader has deleted account
        if (!user && group._id !== 'habitrpg' && members && members[0]) {
          dbGroups.update({
            _id: group._id,
          }, {
            $set: {
              // Set first user as new leader
              leader: members[0],
            },
          }, {
            multi: false,
          }, function (err, res) {
            if (err) return cb1(err);

            console.log('Updated: ', res);
            return cb1();
          });
        } else {
          return cb1();
        }
      });
    }, function (err) {
      if (err) throw err;

      if (lastGroup && lastGroup._id) {
        findGroups(lastGroup._id);
      }
    });
  });
}

findGroups();