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Deciding to develop an Alexa Skill, I had to come up with an idea for a Skill that actually had a lot of utility.
The best idea that I came up with was a voice-activated resistance calculator; I often find myself holding resistors that aren't common values and without a cheat-sheet at hand. Being able to ask for the value is really helpful, and saves me some trouble.
The skill isn't terribly complex under the hood, I have an intent schema that uses four values, of the color_bands custom type, which contains all the colors you can find on a standard four-band resistor. I duplicated myself slightly, using both purple and violet for better compatibility with preferences.
After the four bands are determined and sent to my lambda code, the code works through a series of switch statements to calculate the resistor value. Each switch statements has the default case set to an error that warns the user that the value given was invalid.
There were a few challenges that took a bit of work to mitigate, including the need to have complete help and cancel intents that provide a way to navigate and understand the use of the skill, as well as the tricky nature of Node.js asynchronous code.
/**
* This code takes resistor color bands and returns a completed value
*/
// Route the incoming request based on type (LaunchRequest, IntentRequest,
// etc.) The JSON body of the request is provided in the event parameter.
exports.handler = function (event, context) {
try {
console.log("event.session.application.applicationId=" + event.session.application.applicationId);
if (event.session.application.applicationId !== "amzn1.echo-sdk-ams.app.b8fd96c7-b572-480a-be06-e67d08008cd5") {
context.fail("Invalid Application ID");
}
if (event.session.new) {
onSessionStarted({requestId: event.request.requestId}, event.session);
}
if (event.request.type === "LaunchRequest") {
onLaunch(event.request,
event.session,
function callback(sessionAttributes, speechletResponse) {
context.succeed(buildResponse(sessionAttributes, speechletResponse));
});
} else if (event.request.type === "IntentRequest") {
onIntent(event.request,
event.session,
function callback(sessionAttributes, speechletResponse) {
context.succeed(buildResponse(sessionAttributes, speechletResponse));
});
} else if (event.request.type === "SessionEndedRequest") {
onSessionEnded(event.request, event.session);
context.succeed();
}
} catch (e) {
context.fail("Exception: " + e);
}
};
/**
* Called when the session starts.
*/
function onSessionStarted(sessionStartedRequest, session) {
console.log("onSessionStarted requestId=" + sessionStartedRequest.requestId +
", sessionId=" + session.sessionId);
}
/**
* Called when the user launches the skill without specifying what they want.
*/
function onLaunch(launchRequest, session, callback) {
console.log("onLaunch requestId=" + launchRequest.requestId +
", sessionId=" + session.sessionId);
// Dispatch to your skill's launch.
getWelcomeResponse(callback);
}
/**
* Called when the user specifies an intent for this skill.
*/
function onIntent(intentRequest, session, callback) {
console.log("onIntent requestId=" + intentRequest.requestId +
", sessionId=" + session.sessionId);
var intent = intentRequest.intent,
intentName = intentRequest.intent.name;
// Dispatch to your skill's intent handlers
if ("BandsToValue" === intentName) {
BandsToValue(intent, session, callback);
} else if ("ValueToBand" === intentName) {
ValueToBand(intent, session, callback);
} else if ("AMAZON.HelpIntent" === intentName) {
getHelpResponse(callback);
} else if ("AMAZON.StopIntent" === intentName || "AMAZON.CancelIntent" === intentName) {
handleSessionEndRequest(callback);
} else {
throw "Invalid intent";
}
}
/**
* Called when the user ends the session.
* Is not called when the skill returns shouldEndSession=true.
*/
function onSessionEnded(sessionEndedRequest, session) {
console.log("onSessionEnded requestId=" + sessionEndedRequest.requestId +
", sessionId=" + session.sessionId);
// Add cleanup logic here
}
// --------------- Functions that control the skill's behavior -----------------------
function getWelcomeResponse(callback) {
var sessionAttributes = {};
var speechOutput = "Welcome to Resistor Helper, " +
"I'll tell you the value of a resistor if you give me the colors. If you're ready, can you tell me the four colorbands?";
var shouldEndSession = false;
var reprompt = "I'm ready for the four color bands when you are, with the tolerance band last."
callback(sessionAttributes,
buildSpeechletResponseReprompt(reprompt, speechOutput, shouldEndSession));
}
function getHelpResponse(callback) {
var sessionAttributes = {};
var speechOutput = "Resistor helper takes four color values and returns the calculated resistance and tolerance. The provided values should be something similar to black, brown, red, gold.";
var shouldEndSession = false;
var reprompt = "I'm ready for the four color bands when you are, with the tolerance band last."
callback(sessionAttributes,
buildSpeechletResponseReprompt(reprompt, speechOutput, shouldEndSession));
}
function handleSessionEndRequest(callback) {
var speechOutput = "Thank you for using resistor helper, happy hacking!";
// Setting this to true ends the session and exits the skill.
var shouldEndSession = true;
callback({}, buildSpeechletPlainResponse(speechOutput, shouldEndSession));
}
function BandsToValue(intent, session, callback) {
var value = 0;
var tolerance;
var repromptText = null;
var sessionAttributes = {};
var shouldEndSession = true;
var speechOutput = "";
var badValue = "I'm sorry, I must've misheard. The ";
var badValueCont = " band isn't valid. Could you repeat the colors?"
switch(intent.slots.First.value) {
case "black":
value += 00;
break;
case "brown":
value += 10;
break;
case "red":
value += 20;
break;
case "orange":
value += 30;
break;
case "yellow":
value += 40;
break;
case "green":
value += 50;
break;
case "blue":
value += 60;
break;
case "violet":
value += 70;
break;
case "purple":
value += 70;
break;
case "grey":
value += 80;
break;
case "white":
value += 90;
break;
default:
ErrorReprompt(badValue+"first"+badValueCont, callback);
break;
}
switch(intent.slots.Second.value) {
case "black":
value += 0;
break;
case "brown":
value += 1;
break;
case "red":
value += 2;
break;
case "orange":
value += 3;
break;
case "yellow":
value += 4;
break;
case "green":
value += 5;
break;
case "blue":
value += 6;
break;
case "violet":
value += 7;
break;
case "purple":
value += 7;
break;
case "grey":
value += 8;
break;
case "white":
value += 9;
break;
default:
ErrorReprompt(badValue+"second"+badValueCont, callback);
break;
}
switch(intent.slots.Third.value) {
case "black":
value *= 1;
break;
case "brown":
value *= 10;
break;
case "red":
value *= 100;
break;
case "orange":
value *= 1000;
break;
case "yellow":
value *= 10000;
break;
case "green":
value *= 100000;
break;
case "blue":
value *= 1000000;
break;
case "violet":
value *= 10000000;
break;
case "purple":
value *= 10000000;
break;
case "gold":
value *= 0.1;
break;
case "silver":
value *= 0.01;
break;
default:
ErrorReprompt(badValue+"third"+badValueCont, callback);
break;
}
switch(intent.slots.Fourth.value) {
case "brown":
tolerance = 1;
break;
case "red":
tolerance = 2;
break;
case "green":
tolerance = 0.5;
break;
case "blue":
tolerance = 0.25;
break;
case "violet":
tolerance = 0.1;
break;
case "purple":
tolerance = 0.05;
break;
case "gold":
tolerance = 5;
break;
case "silver":
tolerance = 10;
break;
default:
ErrorReprompt(badValue+"fourth"+badValueCont, callback);
break;
}
speechOutput = "The resistor value is "
+value+" ohms, with a tolerance of plus or minus "
+tolerance+" percent.";
callback(sessionAttributes,
buildSpeechletPlainResponse(speechOutput, shouldEndSession));
}
function ValueToBands(intent, session, callback) {
var repromptText = null;
var sessionAttributes = {};
var shouldEndSession = true;
var speechOutput = "";
speechOutput = "The color bands should be ";
callback(sessionAttributes,
buildSpeechletPlainResponse(speechOutput, shouldEndSession));
}
function ErrorReprompt(errorText, callback){
callback(null, buildSpeechletPlainResponse(errorText, false));
}
// --------------- Helpers that build all of the responses -----------------------
function buildSpeechletResponse(title, output, repromptText, shouldEndSession) {
return {
outputSpeech: {
type: "PlainText",
text: output
},
card: {
type: "Simple",
title: "SessionSpeechlet - " + title,
content: "SessionSpeechlet - " + output
},
reprompt: {
outputSpeech: {
type: "PlainText",
text: repromptText
}
},
shouldEndSession: shouldEndSession
};
}
function buildSpeechletResponseReprompt(output, repromptText, shouldEndSession) {
return {
outputSpeech: {
type: "PlainText",
text: output
},
reprompt: {
outputSpeech: {
type: "PlainText",
text: repromptText
}
},
shouldEndSession: shouldEndSession
};
}
function buildSpeechletPlainResponse(output, shouldEndSession) {
return {
outputSpeech: {
type: "PlainText",
text: output
},
shouldEndSession: shouldEndSession
};
}
function buildResponse(sessionAttributes, speechletResponse) {
return {
version: "1.0",
sessionAttributes: sessionAttributes,
response: speechletResponse
};
}
{
"intents": [
{
"intent": "BandsToValue",
"slots": [
{
"name": "First",
"type": "color_bands"
},
{
"name": "Second",
"type": "color_bands"
},
{
"name": "Third",
"type": "color_bands"
},
{
"name": "Fourth",
"type": "color_bands"
}
]
},
{
"intent": "AMAZON.CancelIntent"
},
{
"intent": "AMAZON.StopIntent"
},
{
"intent": "AMAZON.HelpIntent"
}
]
}
Connor A. Huffine
2 projects • 6 followers
Electrical engineering undergrad at Old Dominion University
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