【Alexa】hostedスキル起動中の変数を保存する

#はじめに
Alexaスキル起動中に使用する変数を保存、読み出しする方法を記載します。

#準備
新機能 hostedスキルで作成するの章を進めてスキルをテスト出来るところまで進めてください。
参考

スキルを開いた後、「こんにちは」など挨拶をした回数をカウントするスキルを作ってみましょう。
なお筆者はこの時点でnode.jpの知識がほとんどありません。

まずはグローバル変数countを使って「こんにちは」と発音した回数を数えてみましょう。

index.js

// This sample demonstrates handling intents from an Alexa skill using the Alexa Skills Kit SDK (v2).
// Please visit https://alexa.design/cookbook for additional examples on implementing slots, dialog management,
// session persistence, api calls, and more.
const Alexa = require('ask-sdk-core');

let count;

const LaunchRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'LaunchRequest';
    },
    handle(handlerInput) {
        const speakOutput = 'こんにちは　などの挨拶の回数をカウントします。';
        count = 0;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const HelloWorldIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'HelloWorldIntent';
    },
    handle(handlerInput) {
        count += 1;
        const speakOutput = `挨拶の回数は ${count}  回です。`;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const HelpIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.HelpIntent';
    },
    handle(handlerInput) {
        const speakOutput = 'これはあなたが作ったアレクサのスキルです。。';

        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const CancelAndStopIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && (Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.CancelIntent'
                || Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.StopIntent');
    },
    handle(handlerInput) {
        const speakOutput = `さようなら。挨拶の回数は ${count}  回でした。`;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .getResponse();
    }
};
const SessionEndedRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'SessionEndedRequest';
    },
    handle(handlerInput) {
        // Any cleanup logic goes here.
        return handlerInput.responseBuilder.getResponse();
    }
};

// The intent reflector is used for interaction model testing and debugging.
// It will simply repeat the intent the user said. You can create custom handlers
// for your intents by defining them above, then also adding them to the request
// handler chain below.
const IntentReflectorHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest';
    },
    handle(handlerInput) {
        const intentName = Alexa.getIntentName(handlerInput.requestEnvelope);
        const speakOutput = `あなたが言ったのは ${intentName} ですね`;

        return handlerInput.responseBuilder
            .speak(speakOutput)
            //.reprompt('add a reprompt if you want to keep the session open for the user to respond')
            .getResponse();
    }
};

// Generic error handling to capture any syntax or routing errors. If you receive an error
// stating the request handler chain is not found, you have not implemented a handler for
// the intent being invoked or included it in the skill builder below.
const ErrorHandler = {
    canHandle() {
        return true;
    },
    handle(handlerInput, error) {
        console.log(`~~~~ Error handled: ${error.stack}`);
        const speakOutput = `すみません、よく聞き取れませんでした。`;

        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};

// The SkillBuilder acts as the entry point for your skill, routing all request and response
// payloads to the handlers above. Make sure any new handlers or interceptors you've
// defined are included below. The order matters - they're processed top to bottom.
exports.handler = Alexa.SkillBuilders.custom()
    .addRequestHandlers(
        LaunchRequestHandler,
        HelloWorldIntentHandler,
        HelpIntentHandler,
        CancelAndStopIntentHandler,
        SessionEndedRequestHandler,
        IntentReflectorHandler, // make sure IntentReflectorHandler is last so it doesn't override your custom intent handlers
    )
    .addErrorHandlers(
        ErrorHandler,
    )
    .lambda();

新しく出てきた命令だけ説明します。

let.js

let count;

グローバル変数としてcountを定義しています。グローバル変数なのでここで定義すればほかの場所でも扱えるようになります。

letは変数定義を行うときに使用します。letは変更可能な変数に、constは値固定の変数に使用します。
constでの定義は値固定となりますが、その変数がオブジェクトの場合、そのオブジェクトのプロパティは変更することが出来ます。

これを実行してみます。

「ノードテストを開く」「こんにちは」で本来であれば、挨拶をした回数をカウントされるはずですが、カウントされ・・・ますね・・・

本来であればhandlerInput.attributesManager.getSessionAttributes();やhandlerInput.attributesManager.Requestattributes();、handlerInput.attributesManager.Persistentattributes();
などを使用して変数の保存と読み込みをするのですが・・・

次回、この件も含めて調査してから修正したいと思います。

handlerInput.attributesManager.getSessionAttributes()を使用した例を下記に示します。

index.js

// This sample demonstrates handling intents from an Alexa skill using the Alexa Skills Kit SDK (v2).
// Please visit https://alexa.design/cookbook for additional examples on implementing slots, dialog management,
// session persistence, api calls, and more.
const Alexa = require('ask-sdk-core');

const LaunchRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'LaunchRequest';
    },
    handle(handlerInput) {
        const speakOutput = 'こんにちは　などの挨拶の回数をカウントします。';
        const attr = handlerInput.attributesManager.getSessionAttributes();
        attr.count = 0;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const HelloWorldIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'HelloWorldIntent';
    },
    handle(handlerInput) {
        const attr = handlerInput.attributesManager.getSessionAttributes();
        let count = attr.count;
        count += 1;
        attr.count = count;
        const speakOutput = `挨拶の回数は ${count}  回です。`;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const HelpIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.HelpIntent';
    },
    handle(handlerInput) {
        const speakOutput = 'これはあなたが作ったアレクサのスキルです。。';

        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};
const CancelAndStopIntentHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest'
            && (Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.CancelIntent'
                || Alexa.getIntentName(handlerInput.requestEnvelope) === 'AMAZON.StopIntent');
    },
    handle(handlerInput) {
        const attr = handlerInput.attributesManager.getSessionAttributes();
        let count = attr.count;
        const speakOutput = `さようなら。挨拶の回数は ${count}  回でした。`;
        return handlerInput.responseBuilder
            .speak(speakOutput)
            .getResponse();
    }
};
const SessionEndedRequestHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'SessionEndedRequest';
    },
    handle(handlerInput) {
        // Any cleanup logic goes here.
        return handlerInput.responseBuilder.getResponse();
    }
};

// The intent reflector is used for interaction model testing and debugging.
// It will simply repeat the intent the user said. You can create custom handlers
// for your intents by defining them above, then also adding them to the request
// handler chain below.
const IntentReflectorHandler = {
    canHandle(handlerInput) {
        return Alexa.getRequestType(handlerInput.requestEnvelope) === 'IntentRequest';
    },
    handle(handlerInput) {
        const intentName = Alexa.getIntentName(handlerInput.requestEnvelope);
        const speakOutput = `あなたが言ったのは ${intentName} ですね`;

        return handlerInput.responseBuilder
            .speak(speakOutput)
            //.reprompt('add a reprompt if you want to keep the session open for the user to respond')
            .getResponse();
    }
};

// Generic error handling to capture any syntax or routing errors. If you receive an error
// stating the request handler chain is not found, you have not implemented a handler for
// the intent being invoked or included it in the skill builder below.
const ErrorHandler = {
    canHandle() {
        return true;
    },
    handle(handlerInput, error) {
        console.log(`~~~~ Error handled: ${error.stack}`);
        const speakOutput = `すみません、よく聞き取れませんでした。`;

        return handlerInput.responseBuilder
            .speak(speakOutput)
            .reprompt(speakOutput)
            .getResponse();
    }
};

// The SkillBuilder acts as the entry point for your skill, routing all request and response
// payloads to the handlers above. Make sure any new handlers or interceptors you've
// defined are included below. The order matters - they're processed top to bottom.
exports.handler = Alexa.SkillBuilders.custom()
    .addRequestHandlers(
        LaunchRequestHandler,
        HelloWorldIntentHandler,
        HelpIntentHandler,
        CancelAndStopIntentHandler,
        SessionEndedRequestHandler,
        IntentReflectorHandler, // make sure IntentReflectorHandler is last so it doesn't override your custom intent handlers
    )
    .addErrorHandlers(
        ErrorHandler,
    )
    .lambda();