How can I get the return result from aggregate?

1

I have tried to use meteorhacks:aggregate package and I would like to get the return result from aggregate.
Please help to verify my code which it does not work:

Registers.js


import React, { Component } from 'react';
import PropTypes from 'prop-types';
import { Link } from 'react-router-dom';
import { Table, Alert, Button } from 'react-bootstrap';
import { Meteor } from 'meteor/meteor';
import { createContainer } from 'meteor/react-meteor-data';
import { Registers } from '../../api/registers';

const XLSX = require('xlsx');

const handleRemove = (registerId) => {
	if (confirm('Are you sure? This is permanent!')) {
		Meteor.call('registers.remove', registerId, (error) => {
			if (error) {
				console.log(error.reason, 'danger');
			} else {
				console.log('success');
			}
		});
	}
};

const gettotalAmount = () => {
	Meteor.call('getAmount');
	console.log(total);
};

const DSRegisters = ({ registers, totalCount, match, history }) => (
		  	<div className="Registers">
    			<div className="page-header clearfix">
      				<h4>{gettotalAmount}</h4>
===Omitted===
);

DSRegisters.propTypes = {
  registers: PropTypes.arrayOf(PropTypes.object).isRequired,
  totalCount: PropTypes.number.isRequired,
  match: PropTypes.object.isRequired,
  history: PropTypes.object.isRequired,
};

export default createContainer(() => {
  const subscription = Meteor.subscribe('registers');
  return {
    registers: Registers.find({}, { sort: { createdAt: 1 } }).fetch(),
    totalCount: Registers.find({}).count(),
  };
}, DSRegisters);

api/registers.js

import { Meteor } from 'meteor/meteor';
import { Mongo } from 'meteor/mongo';
import { check } from 'meteor/check';

export const Registers = new Mongo.Collection('registers');
const XLSX = require('xlsx');



Meteor.methods({
	'getAmount': function getsummaryamount(){
		return Registers.aggregate(
			{ $group: {
				_id: null,
				total: { $sum: '$amount' }}
				}
		);
	},
=== Omitted ===