Javascript Node.js:无法读取未定义的属性[…]

我目前正在为Amazon Alexa编写node.js代码。 我尝试写入REST服务器，并希望通过alexa的演讲输出更改，我也在使用AlexaSDK。我得到这个错误：

TypeError: Cannot read property 'request' of undefined
at writeIntent (/var/task/index.js:41:14)
at /var/task/index.js:125:25
at IncomingMessage.<anonymous> (/var/task/getRestData.js:6:13)
at emitOne (events.js:77:13)
at IncomingMessage.emit (events.js:169:7)
at IncomingMessage.Readable.read (_stream_readable.js:360:10)
at flow (_stream_readable.js:743:26)
at resume_ (_stream_readable.js:723:3)
at nextTickCallbackWith2Args (node.js:437:9)
at process._tickDomainCallback (node.js:392:17)

这是index.js内部的意图处理程序中的代码：

var rest = require('./getRestData');
slot = 'Weather';
rest.getRestData('varWeatherState', function (state) {
    rest.getRestData('varWeatherTemperature', function (temp) {
        report += slot + ', the weather is ' + state
         + ', the temperature is ' + temp;
        writeIntent(slot, report, 'varTheme', this.event, this.context);
        writeIntent((new Date).getTime(), '',
         'varThemeTrigger', this.event, this.context);
    });
});

exports.handler = function (event, context) {
    //init alexa-sdk
    var Alexa = require('alexa-sdk');
    var alexa = Alexa.handler(event, context);
    alexa.appId = 'amzn1.ask.skill.2732c691-3bcc-4741-80f9-ddf57405be70';
    alexa.registerHandlers(handlers);
    alexa.execute();

};

这是getRestData函数：

//main helper function for write-intents
function writeIntent(slot, report, slotURL, event, context) {
var http = require('http');

var options = {
    host: '1.2.345.678',
    path: '/path/' + slotURL,
    port: '8020',
    method: 'POST',
    'Content-Type': 'application/json'
};

callback = function (response) {

    var str = '';

    response.on('data', function (chunk) {
        str += chunk;
    });

    response.on('end', function () {
        if (report.toString() !== '') {
            output(report, context);
        }
    });
};


//write alexa slot to server
if (event.request.type === "IntentRequest") {

    var req = http.request(options, callback);
    var postData = '{"$type":"string","?value":"' + slot + '"}';

    req.write(postData);
    req.end();
    }
}

var getRestData = function (node, callback) {
    var http = require('http');
    var url = 'http://website.com/' + node + '?value';
    http.get(url, function (response) {
        response.on('data', function (data) {
            callback(data);
        });
    });
}

exports.getRestData = getRestData;

事件在index.js中定义为参数：

var rest = require('./getRestData');
slot = 'Weather';
rest.getRestData('varWeatherState', function (state) {
    rest.getRestData('varWeatherTemperature', function (temp) {
        report += slot + ', the weather is ' + state
         + ', the temperature is ' + temp;
        writeIntent(slot, report, 'varTheme', this.event, this.context);
        writeIntent((new Date).getTime(), '',
         'varThemeTrigger', this.event, this.context);
    });
});

exports.handler = function (event, context) {
    //init alexa-sdk
    var Alexa = require('alexa-sdk');
    var alexa = Alexa.handler(event, context);
    alexa.appId = 'amzn1.ask.skill.2732c691-3bcc-4741-80f9-ddf57405be70';
    alexa.registerHandlers(handlers);
    alexa.execute();

};

在getRestData函数之外，我可以使用此.event访问事件。 如何通过getRestData将事件（和上下文）馈送到WriteContent？