ReactJS组件函数调用此函数，props未定义

这可能是一个简单的React问题，但是我是一个新手。在完成了一些教程和出色的在线课程之后，我正在尝试我的第一个适当的ReactJS项目。我也咬过ES6和JSX，所以可能是问题所在。基本上，使用传入的数组作为props，然后调用子函数对数据结构进行登录，我想将被称为onClick的函数作为props传入，但是“ this”在函数中未定义，尽管它是被传递给array.map函数...

import React from 'react';
import { Link, Location } from 'react-router';

import moment from 'moment';
import _ from 'lodash';

import IBoxTools from '../common/iboxTools';

class Timesheets extends React.Component {

    componentDidMount() {
        $('.timesheets li button').tooltip();
    }

    render() {

        const showTimesheets = function (timesheets) {

            if (timesheets && timesheets.length) {
                return (
                    <div>
                        <ul className="list-group timesheets">
                            {timesheets.map(timesheetCandidateRow, this)}
                        </ul>
                        <Link to="/timesheets" className="btn btn-primary">View all timesheets</Link>
                    </div>
                );
            }
            else {
                return (
                    <div>
                        <p>There are currently no timesheets requiring action</p>
                        <a className="btn btn-primary" href="#">View all timesheets</a>
                    </div>);
            }
        }

        const timesheetCandidateRow = function (timesheetCandidate) {
            var candidateName = timesheetCandidate.candidate.forename + ' ' + timesheetCandidate.candidate.surname;
            return (
                <li className="list-group-item" key={timesheetCandidate.id}>
                    <div>
                        <h4 className="list-group-item-heading">{candidateName}<br /><small>{timesheetCandidate.candidate.title}</small></h4>
                        <table className="table table-condensed">
                            <tbody>
                                {timesheetCandidate.timesheets.map(timesheetRow, this)}
                            </tbody>
                        </table>
                    </div>
                </li>
            );
        }

        const timesheetRow = function (timesheet) {
            var timesheetDate = moment(timesheet.date).format('dddd Do MMM');
            if (timesheet.startTime) {
                timesheetDate = timesheetDate + ' ' + timesheet.startTime + ' to ' + timesheet.endTime;
            }
            return (
                <tr key={timesheet.id}>
                    <td>{timesheetDate}</td>
                    <td>{timesheet.charge}</td>
                    <td style={{ width: 70 }}>
                        <div className="btn-group">
                            <button className="btn btn-success btn-xs" onClick={this.props.onAccept} title="Accept" data-toggle="tooltip" data-placement="bottom"><i className="fa fa-check"></i></button>
                            <button className="btn btn-danger btn-xs" onClick={this.props.onReject} title="Reject" data-toggle="tooltip" data-placement="bottom"><i className="fa fa-close"></i></button>
                        </div>
                    </td>
                </tr>
            );
        }

        return (
            <div className="ibox float-e-margins">
                <div className="ibox-title">
                    <h5>
                        <span className="fa-stack">
                            <i className="fa fa-square-o fa-stack-2x"></i>
                            <i className="fa fa-check fa-stack-1x"></i>
                        </span> Timesheets
                                </h5>
                    <IBoxTools />
                </div>
                <div className="ibox-content">
                    {showTimesheets(this.props.timesheets)}
                </div>
            </div>
        );
    }

}

Timesheets.propTypes = {
    timesheets: React.PropTypes.array,
    onAccept: React.PropTypes.func.isRequired,
    onReject: React.PropTypes.func.isRequired
}

export default Timesheets;

因此，在render方法的const中，“ this”是未定义的。有什么帮助吗？

谢谢。