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alexa-js
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Description

A framework for Alexa (Amazon Echo) apps using Node.js

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Table of Contents

alexa-app

A Node module to simplify the development of Alexa skills (applications.)

NPM Build Status Coverage Status

Stable Release

You're reading the documentation for the next release of alexa-app, which should be 5.0.0. Please see CHANGELOG and make sure to read UPGRADING when upgrading from a previous version. The current stable release is 4.2.3.

Introduction

This module parses HTTP JSON requests from the Alexa platform and builds the JSON response that consumed by an Alexa-compatible device, such as the Echo.

It provides a DSL for defining intents, convenience methods to more easily build the response, handle session objects, and add cards.

The intent schema definition and sample utterances are included in your application's definition, making it very simple to generate hundreds (or thousands!) of sample utterances with a few lines.

This module provides a way to host a standalone web service for an Alexa skill. If you're looking for a full-fledged application server or the ability to host multiple skills, check out alexa-app-server.

Features

  • simplified handling of requests and generating responses
  • support for asynchronous handlers
  • easy connection into AWS Lambda or Node.js Express, etc.
  • auto-generation of intent schema and sample utterances
  • support for session data
  • comprehensive test suite
  • TypeScript type definitions for type validation, IDE autocompletion, etc

Examples

AWS Lambda

Amazon skills that use alexa-app have a built-in

handler
method to handle calls from AWS Lambda. You need to make sure that the Handler is set to
index.handler
, which is the default value.
var alexa = require("alexa-app");
var app = new alexa.app("sample");

app.intent("number", { "slots": { "number": "AMAZON.NUMBER" }, "utterances": ["say the number {-|number}"] }, function(request, response) { var number = request.slot("number"); response.say("You asked for the number " + number); } );

// connect the alexa-app to AWS Lambda exports.handler = app.lambda();

For backwards compatibility, or if you wish to change the Handler mapping to something other than index.handler, you can use the lambda() function.

A full lambda example is available here.

Express

var express = require("express");
var alexa = require("alexa-app");
var express_app = express();

var app = new alexa.app("sample");

app.intent("number", { "slots": { "number": "AMAZON.NUMBER" }, "utterances": ["say the number {-|number}"] }, function(request, response) { var number = request.slot("number"); response.say("You asked for the number " + number); } );

// setup the alexa app and attach it to express before anything else app.express({ expressApp: express_app });

// now POST calls to /sample in express will be handled by the app.request() function // GET calls will not be handled

// from here on, you can setup any other express routes or middleware as normal

The express function accepts the following parameters.

  • expressApp
    the express app instance to attach to
  • router
    the express router instance to attach to
  • endpoint
    the path to attach the express app or router to (e.g., passing
    'mine'
    attaches to
    /mine
    )
  • checkCert
    when true, applies Alexa certificate checking (default: true)
  • debug
    when true, sets up the route to handle GET requests (default: false)
  • preRequest
    function to execute before every POST
  • postRequest
    function to execute after every POST

Either

expressApp
or
router
is required.

A full express example is available here.

Heroku Quickstart

Want to get started quickly with alexa-app and Heroku? Simply click the button below!

Deploy to Heroku

API

Skills define handlers for launch, intent, and session end, just like normal Alexa development. The alexa-app module provides a layer around this functionality that simplifies the interaction. Each handler gets passed a request and response object, which are custom for this module.

request

// return the type of request received (LaunchRequest, IntentRequest, SessionEndedRequest)
String request.type()

// return the value passed in for a given slot name String request.slot("slotName")

// return the Slot object Slot request.slots["slotName"]

// return the intent's confirmationStatus String request.confirmationStatus

// check if the intent is confirmed Boolean request.isConfirmed()

// return the Dialog object Dialog request.getDialog()

// check if you can use session (read or write) Boolean request.hasSession()

// return the session object Session request.getSession()

// return the router object Router request.getRouter()

// return the request context request.context

// the raw request JSON object request.data

response

The response JSON object is automatically built for you. All you need to do is tell it what you want to output.

// tell Alexa to say something; multiple calls to say() will be appended to each other
// all text output is treated as SSML
response.say(String phrase)

// empty the response text response.clear()

// tell Alexa to re-prompt the user for a response, if it didn't hear anything valid response.reprompt(String phrase)

// return a card to the user's Alexa app // for Object definition @see https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/alexa-skills-kit-interface-reference#card-object // skill supports card(String title, String content) for backwards compat of type "Simple" response.card(Object card)

// return a card instructing the user how to link their account to the skill // this internally sets the card response response.linkAccount()

// play audio stream (send AudioPlayer.Play directive) @see https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/custom-audioplayer-interface-reference#play-directive // skill supports stream(String url, String token, String expectedPreviousToken, Integer offsetInMilliseconds) response.audioPlayerPlayStream(String playBehavior, Object stream)

// stop playing audio stream (send AudioPlayer.Stop directive) response.audioPlayerStop()

// clear audio player queue (send AudioPlayer.ClearQueue directive) // clearBehavior is "CLEAR_ALL" by default response.audioPlayerClearQueue([ String clearBehavior ])

// tell Alexa whether the user's session is over; sessions end by default // pass null or undefined to leave shouldEndSession undefined in the response, to satisfy newer API's // you can optionally pass a reprompt message response.shouldEndSession(boolean end [, String reprompt] )

// send the response to the Alexa device (success) immediately // this returns a promise that you must return to continue the // promise chain. Calling this is optional in most cases as it // will be called automatically when the handler promise chain // resolves, but you can call it and return its value in the // chain to send the response immediately. You can also use it // to send a response from post after failure. async response.send()

// trigger a response failure // the internal promise containing the response will be rejected, and should be handled by the calling environment // instead of the Alexa response being returned, the failure message will be passed // similar to response.send(), you must return the value returned from this call to continue the promise chain // this is equivalent to calling throw message in handlers // NOTE: this does not generate a response compatible with Alexa, so when calling it explicitly you may want to handle the response with .error or .post async response.fail(String message)

// calls to response can be chained together return response.say("OK").send()

Building SSML Responses

Use ssml-builder to build SSML responses.

Example using basic SSML tags: ```javascript var Speech = require('ssml-builder');

var speech = new Speech() .say('Hello') .pause('1s') .say('fellow Alexa developers') .pause('500ms') .say('Testing phone numbers') .sayAs({ word: "+1-234-567-8900", interpret: "telephone" });

// change 'true' to 'false' if you want to include the surrounding tag var speechOutput = speech.ssml(true); response.say(speechOutput); ```

Example using Amazon SSML specific tags: ```javascript var AmazonSpeech = require('ssml-builder/amazon_speech');

var speech = new AmazonSpeech() .say('Hello') .pause('1s') .whisper('I can see you when you are sleeping') .pause('500ms') .say('Is your phone number still') .sayAs({ word: "+1-234-567-8900", interpret: "telephone" });

var speechOutput = speech.ssml(); response.say(speechOutput); ```

Example using multiple reprompts. The reprompts are spoken to the user if they do not respond to the main prompt or say something that does not map to a defined intent:

javascript
response.say('What is your request?')
  .reprompt('Sorry, I didn\'t catch that.')
  .reprompt('What is your request?');

session

// check if you can use session (read or write)
Boolean request.hasSession()

// get the session object var session = request.getSession()

// set a session variable // by defailt, Alexa only persists session variables to the next request // the alexa-app module makes session variables persist across multiple requests // Note that you must use .set or .clear to update // session properties. Updating properties of attributeValue // that are objects will not persist until .set is called session.set(String attributeName, String attributeValue)

// return the value of a session variable String session.get(String attributeName)

// session details, as passed by Amazon in the request // for Object definition @see https://developer.amazon.com/public/solutions/alexa/alexa-skills-kit/docs/alexa-skills-kit-interface-reference#session-object session.details = { ... }

router

// get router object
// every method of the router returns a promise, so you can chain them or just return it back to alexa-app
var router = request.getRouter()

// route request to 'MySuperIntent' intent handler Promise router.intent('MySuperIntent')

// route request to Launch handler Promise router.launch()

// route request to session ended handler Promise router.sessionEnded()

// route request to audio player handler Promise router.audioPlayer('PlaybackNearlyFinished')

// route request to playback controller handler Promise router.playbackController('NextCommandIssued')

// route request to display element selected handler Promise router.displayElementSelected()

// route request to custom handler Promise router.custom('CrazyCustomEvent')

slot

// get the slot object
var slot = request.slots["slotName"]

// return the slot's name String slot.name

// return the slot's value String slot.value

// return the slot's confirmationStatus String slot.confirmationStatus

// return the slot's resolutions SlotResolution[] slot.resolutions

// check if the slot is confirmed Boolean slot.isConfirmed()

// return the n-th resolution SlotResolution slot.resolution(Integer n)

slotResolution

// get the resolution status code
String resolution.status

// get the list of resolution values ResolutionValue resolution.values

// check if the resolution is matched Boolean resolution.isMatched()

// Get the first resolution value ResolutionValue resolution.first()

resolutionValue

// get the value name
String resolutionValue.name

// get the value id String resolutionValue.id

Request Handlers

Your app can define a single handler for the

Launch
event and the
SessionEnded
event, and multiple intent handlers.

For switching intents, redirecting from one handler to other and other routing tasks you can use router.

LaunchRequest

app.launch(function(request, response) {
  response.say("Hello World");
  response.card("Hello World", "This is an example card");
});

IntentRequest

Define the handler for multiple intents using multiple calls to

intent()
. Additional Intent configuration schema like slots and sample utterances can also be passed to
intent()
, which is detailed below. Intent handlers that don't return an immediate response (because they do some asynchronous operation) must return a Promise. The response will be sent when the promise is resolved and fail when the promise is rejected. See example further below.
app.intent("live", {
    "dialog": {
      type: "delegate",
    },
    "slots": {
      "city": "AMAZON.US_CITY"
    },
    "utterances": [
      "in {-|city}"
    ]
  },
  function(request, response) {
    response.say("You live in " + request.slot("city"));
  }
);

app.intent("vacation", function(request, response) { response.say("You're now on vacation."); });

AMAZON Specific Intents

Amazon has specific intents that have to do with basic functionality of your skill that you must add. Some examples of this are

AMAZON.HelpIntent
,
AMAZON.StopIntent
, and
AMAZON.CancelIntent
. Here are examples of how you would specify these types of intents.
app.intent("AMAZON.HelpIntent", {
    "slots": {},
    "utterances": []
  },
  function(request, response) {
    var helpOutput = "You can say 'some statement' or ask 'some question'. You can also say stop or exit to quit.";
    var reprompt = "What would you like to do?";
    // AMAZON.HelpIntent must leave session open -> .shouldEndSession(false)
    response.say(helpOutput).reprompt(reprompt).shouldEndSession(false);
  }
);

app.intent("AMAZON.StopIntent", { "slots": {}, "utterances": [] }, function(request, response) { var stopOutput = "Don't You Worry. I'll be back."; response.say(stopOutput); } );

app.intent("AMAZON.CancelIntent", { "slots": {}, "utterances": [] }, function(request, response) { var cancelOutput = "No problem. Request cancelled."; response.say(cancelOutput); } );

You do not need to pass any utterances or slots into these intents. Also when specifying the name of the intent just use the exact name Amazon provides.

Display Element Selected

Define the handler for when a user selects an element displayed on alexa touch enabled device. For instance the Echo Show.

app.displayElementSelected(function(request, response) {
  // The request object selectedElementToken will be populated with the token that was registered
  // the element in the display directive. To get the token associated with the directive itself,
  // it is populated on the request.context.Display.token property.
  handleRequestForTouchEvent(request.selectedElementToken)
})

SessionEndRequest

app.sessionEnded(function(request, response) {
  // cleanup the user's server-side session
  logout(request.userId);
  // no response required
});

AudioPlayer Event Request

Define the handler for multiple events using multiple calls to

audioPlayer()
. You can define only one handler per event. Event handlers that don't return an immediate response (because they do some asynchronous operation) must return a Promise.

You can define handlers for the following events:

  • PlaybackStarted
  • PlaybackFinished
  • PlaybackStopped
  • PlaybackNearlyFinished
  • PlaybackFailed

Please note: *

PlaybackStarted
and
PlaybackFinished
 accept only
Stop
 or 
ClearQueue
 directive in response. *
PlaybackStopped
does not accept any response. *
PlaybackNearlyFinished
and
PlaybackFailed
 accept any AudioPlayer directive in response.

Read more about AudioPlayer request types in AudioPlayer Interface Doc.

The following example will return

play
directive with a next audio on
AudioPlayer.PlaybackNearlyFinished
request.
app.audioPlayer("PlaybackNearlyFinished", function(request, response) {
  // immediate response
  var stream = {
    "url": "https://next-song-url",
    "token": "some_token",
    "expectedPreviousToken": "some_previous_token",
    "offsetInMilliseconds": 0
  };
  response.audioPlayerPlayStream("ENQUEUE", stream);
});

See an example of asynchronous response below.

app.audioPlayer("PlaybackFinished", function(request, response) {
  // async response
  return getNextSongFromDBAsync()
  .then(function(url, token) {
    var stream = {
      "url": url,
      "token": token,
      "expectedPreviousToken": "some_previous_token",
      "offsetInMilliseconds": 0
    };
    response.audioPlayerPlayStream("ENQUEUE", stream);
  });
});

PlaybackController Event Request

PlaybackController events are sent to your skill when the user interacts with player controls on a device. Define multiple handlers for various events by making multiple calls to

playbackController
with each event type.

You can define handlers for the following events:

  • PlayCommandIssued
  • PauseCommandIssued
  • NextCommandIssued
  • PreviousCommandIssued

Read more about PlaybackController requests in the PlaybackController Interface Reference.

The following example will send a play directive to the device when a user presses the "next" button.

app.playbackController('NextCommandIssued', (request, response) => {
  var stream = {
    "url": "https://next-song-url",
    "token": "some_token",
    "expectedPreviousToken": "some_previous_token",
    "offsetInMilliseconds": 0
  };
  response.audioPlayerPlayStream("REPLACE_ALL", stream);
});

Note that some device interactions don't always produce PlaybackController events. See the PlaybackController Interface Introduction for more details.

Other Event Request

Handle any new requests that don't have an explicit handler type available (such as new or pre-release features) using the general

on()
and passing the event type.

The following example will handle an imaginary request of type

DeviceEngine.InputHandler
as if it were added to the Alexa API.
app.on('DeviceEngine.InputHandler', (request, response, request_json) => {
  response.say("You triggered an event from device " + request_json.request.event.deviceName);
});

Note that the raw request json is sent as the 3rd parameter to make sure the handler function has access to all data in the case that the request format differs from other handler types.

Execute Code On Every Request

In addition to specific event handlers, you can define functions that will run on every request.

pre()

Executed before any event handlers. This is useful to setup new sessions, validate the

applicationId
, or do any other kind of validations. You can perform asynchronous functionality in
pre
by returning a Promise.
app.pre = function(request, response, type) {
  if (request.applicationId != "amzn1.echo-sdk-ams.app.000000-d0ed-0000-ad00-000000d00ebe") {
    // fail ungracefully
    throw "Invalid applicationId";
    // `return response.fail("Invalid applicationId")` will also work
  }
};

// Asynchronous app.pre = function(request, response, type) { return db.getApplicationId().then(function(appId) { if (request.applicationId != appId) { throw new Error("Invalid applicationId"); } }); };

Note that the

post()
method still gets called, even if the
pre()
function calls
send()
or
fail()
. The post method can always override anything done before it.

post()

The last thing executed for every request. It is even called if there is an exception or if a response has already been sent. The

post()
function can change anything about the response. It can even turn a
return response.fail()
into a
return respond.send()
with entirely new content. If
post()
is called after an exception is thrown, the exception itself will be the 4th argument.

You can perform asynchronous functionality in

pre
by returning a Promise similar to
pre
or any of the handlers.
app.post = function(request, response, type, exception) {
  if (exception) {
    // always turn an exception into a successful response
    return response.clear().say("An error occured: " + exception).send();
  }
};

Schema and Utterances

The alexa-app module makes it easy to define your intent schema and generate many sample utterances. Optionally pass your schema definition along with your intent handler, and extract the generated content using either the

schemas.intent()
and
utterances()
functions on your app (if using the normal Developer portal),
schemas.skillBuilder()
if using the new Skill Builder beta, or
schemas.askcli()
if using the
ask-cli
tool.

Schema Syntax

Pass an object with two properties: slots and utterances.

app.intent("sampleIntent", {
    "slots": {
      "NAME": "AMAZON.US_FIRST_NAME",
      "AGE": "AMAZON.NUMBER"
    },
    "utterances": [
      "my {name is|name's} {NAME} and {I am|I'm} {-|AGE}{ years old|}"
    ]
  },
  function(request, response) { ... }
);

slots

The slots object is a simple

name: type
mapping. The type must be one of Amazon's built-in slot types, such as
AMAZON.DATE
or
AMAZON.NUMBER
.

custom slot types

Custom slot types are supported via the following syntax.

app.intent("sampleIntent", {
    "slots": {
      "CustomSlotName": "CustomSlotType"
    },
    "utterances": [
      "airport {information|status} for {-|CustomSlotName}"
    ]
  },
  function(request, response) { ... }
);

This will result in the following utterance list.

sampleIntent     airport information for {CustomSlotName}
sampleIntent     airport status for {CustomSlotName}

Note that the "CustomSlotType" type values must be specified in the Skill Interface's Interaction Model for the custom slot type to function correctly.

custom slot type values

If you have custom slot types, you can define your custom slot type values as well. Custom values can either be simple strings, or more full-fledged objects if you want to take advantage of Skill Builder features like synonyms. If using synonyms, you can also take advantage of utterance expansion from alexa-utterances (including dictionary), as described below.

testApp.customSlot("animal", ["cat", "dog"]);

OR

testApp.customSlot("animal", [{
  value: "dog",
  id: "canine",
  synonyms: ["doggo", "pup{per|}", "woofmeister"]
}]);

utterances

The utterances syntax allows you to generate many (hundreds or even thousands) of sample utterances using just a few samples that get auto-expanded. Any number of sample utterances may be passed in the utterances array.

This module internally uses alexa-utterances to expand these convenient strings into a format that alexa understands. Read the documentation there for a thorough set of examples on how to use this.

Using a Dictionary

Several intents may use the same list of possible values, so you want to define them in one place, not in each intent schema. Use the app's dictionary.

app.dictionary = {"colors":["red","green","blue"]};
...
"my favorite color is {colors|FAVEORITE_COLOR}"
"I like {colors|COLOR}"

Generating Schema and Utterances Output

Intent Schema Syntax

If you are using the normal Amazon developer portal, the

schemas.intent()
and
utterances()
functions will generate an intent schema JSON string and a list of utterances, respectively.

See example/express.js for one way to output this data.

// returns a String representation of an Intent Schema JSON object
app.schemas.intent() =>

{ "intents": [{ "intent": "MyColorIsIntent", "slots": [{ "name": "Color", "type": "AMAZON.Color" }] }] }

app.utterances() =>

MyColorIsIntent my color is {dark brown|Color} MyColorIsIntent my color is {green|Color} MyColorIsIntent my favorite color is {red|Color} MyColorIsIntent my favorite color is {navy blue|Color} WhatsMyColorIntent whats my color WhatsMyColorIntent what is my color WhatsMyColorIntent say my color WhatsMyColorIntent tell me my color WhatsMyColorIntent whats my favorite color WhatsMyColorIntent what is my favorite color WhatsMyColorIntent say my favorite color WhatsMyColorIntent tell me my favorite color WhatsMyColorIntent tell me what my favorite color is

Skill Builder Syntax

If you are using the Skill Builder Beta, the

schemas.skillBuilder()
function will generate a single schema JSON string that includes your intents with all of their utterances
app.schemas.skillBuilder() =>

{ "intents": [{ "name": "MyColorIsIntent", "samples": [ "my color is {dark brown|Color}", "my color is {green|Color}", "my favorite color is {red|Color}", "my favorite color is {navy blue|Color}" ], "slots": [{ "name": "Color", "type": "AMAZON.Color", "samples": [] }] }], "types": [{ "name": "MyCustomColor", "values": [{ "id": null, "name": { "value": "aquamarine", "synonyms": ["aqua", "seafoam", "teal"] } }] }]; }

ask-cli Schema

The ask-cli tool accepts a schema in the same format as the Skill Builder, but is structured slightly differently. The

schemas.askcli()
function generates a JSON string suitable to be used with the
ask deploy
command.

This schema format requires you to specify the invocation name for your skill. You can set this for your skill by setting

app.invocationName
. If you need to use different invocation names for the same skill (e.g. you have both a staging and production version), the schema function itself can take in an invocation name which overwrites the app's default.
app.schemas.askcli("favorite color") =>

{ "interactionModel": { "languageModel": { "invocationName": "favorite color" "intents": [{ "name": "MyColorIsIntent", "samples": [ "my color is {dark brown|Color}", "my color is {green|Color}", "my favorite color is {red|Color}", "my favorite color is {navy blue|Color}" ], "slots": [{ "name": "Color", "type": "AMAZON.Color", "samples": [] }] }], "types": [{ "name": "MyCustomColor", "values": [{ "id": null, "name": { "value": "aquamarine", "synonyms": ["aqua", "seafoam", "teal"] } }] }]; } } }

Cards

The

response.card(Object card)
method allows you to send Home Cards on the Alexa app, the companion app available for Fire OS, Android, iOS, and desktop web browsers.

The full specification for the

card
object passed to this method can be found here.

The full specification for the permission card can be found here.

Cards do not support SSML.

If you just want to display a card that presents the user to link their account call

response.linkAccount()
as a shortcut.

Card Examples

Display text only, aka Simple.

response.card({
  type: "Simple",
  title: "My Cool Card", // this is not required for type Simple
  content: "This is the\ncontent of my card"
});

Display text and image, aka Standard.

Make sure to read the restrictions on hosting the images. Must support CORS AND SSL cert signed by an Amazon approved certification authority.

response.card({
  type: "Standard",
  title: "My Cool Card", // this is not required for type Simple or Standard
  text: "Your ride is on the way to 123 Main Street!\nEstimated cost for this ride: $25",
  image: { // image is optional
    smallImageUrl: "https://carfu.com/resources/card-images/race-car-small.png", // required
    largeImageUrl: "https://carfu.com/resources/card-images/race-car-large.png"
  }
});

Display a card that presents the user to grant information to your skill, aka AskForPermissionsConsent.

If the request was for the country and postal code, then the permissions value in this response will be

read::alexa:device:all:address:country_and_postal_code
.
response.card({
  type: "AskForPermissionsConsent",
  permissions: [ "read::alexa:device:all:address" ] // full address
});

Custom Directives

The

response.directive(Object directive)
method allows you to set custom directive objects to devices to perform a specific device-level actions.

The full specification for the

directive
object passed to this method can be found here.

The

alexa-app
library has special handling for AudioPlayer directives, so you only need to use this method for more general custom directives.

The

response.directive
adds your directive object to the directives array in the response. To clear the directives from the response, call
response.getDirectives().clear()
.

Dialog

The full specification for the dialog directives that can be used can be found here. See Custom Directives above for an example on manually sending dialog directives.

Note that skills must meet Alexa's requirements to use the

Dialog
directive.

The

alexa-app
library has special handling for enabling Alexa to handle Dialog directly. To configure
alexa-app
to delegate dialog to Alexa, enable the handling per-intent via the schema:
app.intent("sampleIntent", {
    "dialog": {
      type: "delegate"
    },
    "slots": { ... },
    "utterances": [ ... ],
  },
  function(request, response) { ... }
);

dialog object

// return the Dialog object
Dialog request.getDialog()

// return the intent's dialogState String dialog.dialogState

// check if the intent's dialog is STARTED Boolean dialog.isStarted()

// check if the intent's dialog is IN_PROGRESS Boolean dialog.isInProgress()

// check if the intent's dialog is COMPLETED Boolean dialog.isCompleted()

Error Handling

When handler functions throw exceptions, they will trigger a rejection in the promise chain. If the response has not already been sent,

.post
will be triggered which will allow you to force a successful response. If
post
does not alter the response, then a failed response will be sent. You can use this to throw an exception to or call
return response.fail("message")
to force a failure, but this does not generate a response compatible with Alexa.

The

.error
handler method will capture any errors in the chain. The default behavior of
.error
is to trigger
response.send
if the response has not already been sent, but you can force or continue failure by returning a rejected promise or
throw
ing inside the error handler. Returning a promise allows you to do asynchronous operations in the error handler.

Ideally, you should catch errors in your handlers and respond with an appropriate output to the user. Any exceptions can be handled by a generic error handler which you can define for your app. If you want error handling to be asynchronous, it must return a promise.

app.error = function(exception, request, response) {
  response.say("Sorry, something bad happened");
};

If you do want exceptions to bubble out to the caller (and potentially cause Express to crash, for example), you can throw the exception from the error handler.

app.error = function(exception, request, response) {
  console.error(exception);
  throw exception;
};

Echo Show Support

With the addition of custom directives and support for display elements being selected, this library fully supports the Echo Show. Note that it is up to the developer to detect if the device can handle a display directive. If a display directive is returned to a non-visual device it will throw an error. One technique is to leverage the

app.post
call and remove any directives if the device does not support a UI. For example:
app.post(req, res, type, exception) {
  // If the device does not support display directives then remove them from the response
  if (!system.supportsDisplay(req))) {
    res.response.response.directives = []
  }
}

Please refer to Amazon's documentation for the list of supported template markup.

Asynchronous Handlers Example

If an intent or other request handler (including

pre
and
post
, but not
error
) will return a response later, it must a
Promise
. This tells the alexa-app library not to send the response automatically.

If the Promise resolves, the response will be sent. If it is rejected, it is treated as an error.

app.intent("checkStatus", function(request, response) {
  // `getAsync` returns a Promise in this example. When
  // returning a Promise, the response is sent after it
  // resolves. If rejected, it is treated as an error.
  return http.getAsync("http://server.com/status.html").then(function (rc) {
    response.say(rc.statusText);
  });
});

If you want to respond immediately, you can use

return response.send()
to complete the respones. Using
throw msg
or
return response.fail(msg)
will trigger immediate failure. Note:
.post
is still run once after
response.send()
or
response.fail()
are called.
app.intent("checkStatus", function(request, response) {
  if (currentStatus == "bad") {
    return response.fail("bad status");
  }
  else if (currentStatus == "good") {
    response.say("good status");
    return response.send();
  }

return http.getAsync("http://server.com/status.html").then(function (rc) { if (rc.body == "bad") { throw "bad status"; } response.say("good status"); // return response.send to continue the promise chain return response.send(); }); });

Customizing Default Error Messages

app.messages.NO_INTENT_FOUND = "Why you called dat intent? I don't know bout dat";

See the code for default messages you can override.

Read/write session data

app.launch(function(request, response) {
  request.getSession().set("number", 42);
  response.say("Would you like to know the number?");
  response.shouldEndSession(false);
});

app.intent("tellme", function(request, response) { var session = request.getSession(); response.say("The number is " + session.get("number")); // clear only the 'number' attribute from the session session.clear("number"); });

// the session variables can be entirely cleared, or cleared by key app.intent("clear", function(request, response) { var session = request.getSession(); session.clear(); // or: session.clear("key") to clear a single value response.say("Session cleared!"); });

By default, alexa-app will persist every request session attribute into the response. This way, any session attributes you set will be sent on every subsequent request, as is typical in most web programming environments. If you wish to disable this feature, you can do so by setting

app.persistentSession
to
false
.
var app = new alexa.app("test");
app.persistentSession = false;

Define a custom endpoint name for an app

When mapped to express, the default endpoint for each app is the name of the app. You can customize this using the second parameter to the

app()
method.
var app = new alexa.app("hello", "myEndpointName");

All named apps can be found in the

alexa.apps
object, keyed by name. The value is the app itself.

License

Copyright (c) 2016-2017 Matt Kruse

MIT License, see LICENSE for details.

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