为什么此Alexa自定义技能的Lambda在Node.js中不起作用（Alexa不讲话，超时）

Question

我必须在Intent匹配中向我的mqtt代理发布MQTT消息，以下是无法正常工作的代码。

var mqtt = require('mqtt-async');

function sendMQTTMessage(json)
{
    if(!client || !client.connected)
    {
        console.log('found mqtt client to be not connected');
        if(client)client.end();

        var options = {
        username: 'uname',
        password: 'pass',
        rejectUnauthorized: false,
        clean: true
        };

        client = mqtt.connect('mqtts://ip:8883',options);
        client.on('connect', () => {
            client.publish('alexaIntentMatch', JSON.stringify(json));
            console.log('sent');
        });
    }
    else//publish now
    {
        client.publish('alexaIntentMatch', JSON.stringify(json));
        console.log('sent');
    }
}
const ItineraryIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'itinerary';
    },
    handle(handlerInput) {
        var res = {'intentName':'ITENARY'};
        sendMQTTMessage(res);
        return handlerInput.responseBuilder.speak('You asked for ITENARY').getResponse();}
};

发生的是，当消息成功发送到mqtt代理时，Alexa 不讲话 （在cloudwatch中可以看到请求在8个奇数秒后超时）。

Task timed out after 8.01 seconds

虽然这段代码可以正常工作，

const ItineraryIntentHandler = {
canHandle(handlerInput) {
    return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
        && Alexa.getIntentName(handlerInput.requestEnvelope) === 'itinerary';
},
handle(handlerInput) {let userID = handlerInput.requestEnvelope.context.System.user.userId;
    let client = mqtt.connect('mqtts://ip:8883',{
    username: 'uname',
    password: 'pass',
    rejectUnauthorized: false,
    clean: true
    });
    client.on('connect', () => {
        var res = {'intentName':'ITENARY'};
        client.publish('alexaIntentMatch', JSON.stringify(res));
        console.log('worked');
        client.end();
    });
    return handlerInput.responseBuilder.speak("Today's itinerary is displayed on your TV.").getResponse();}};

这里有什么可错过的傻事吗？

Answer 1

尝试添加async await ：

var mqtt = require('mqtt-async');

async function sendMQTTMessage(json)
{
    if(!client || !client.connected)
    {
        console.log('found mqtt client to be not connected');
        if(client)client.end();

        var options = {
        username: 'uname',
        password: 'pass',
        rejectUnauthorized: false,
        clean: true
        };

        client = mqtt.connect('mqtts://ip:8883',options);
        client.on('connect', () => {
            await client.publish('alexaIntentMatch', JSON.stringify(json));
            console.log('sent');
        });
    }
    else//publish now
    {
        await client.publish('alexaIntentMatch', JSON.stringify(json));
        console.log('sent');
    }
}
const ItineraryIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'itinerary';
    },
    async handle(handlerInput) {
        var res = {'intentName':'ITENARY'};
        await sendMQTTMessage(res);
        return handlerInput.responseBuilder.speak('You asked for ITENARY').getResponse();}
};