Mongo aggregation in feathers.js

'use strict';
​
module.exports = function(app) {
    return function(req, res, next) {
        app.service('things').Model.aggregate([{
            $match: {}
        }, {
            $project: {
                year: {
                    $year: '$createdAt'
                },
                month: {
                    $month: '$createdAt'
                },
                day: {
                    $dayOfMonth: '$createdAt'
                },
                hour: {
                    $hour: '$createdAt'
                },
                minutes: {
                    $minute: '$createdAt'
                },
                "extraData.sentiment": 1
            }
        }, {
            $group: {
                _id: {
                    'year': '$year',
                    'month': '$month',
                    'day': '$day',
                    'hour': '$hour',
                    'minutes': '$minutes',
                },
                count: {
                    $sum: 1
                },
                sentiment: {
                    $avg: "$extraData.sentiment"
                }
            }
        }], function(err, result) {
            if (err) {
                console.log(err);
                res.sendStatus(500);
                return;
            }
            res.send(result);
        });
​
        // next();
    };
};