In this module, you will build Cake Walk, a simple skill that asks the user for their birthday, remembers it, tells them how many days until their next birthday, and wishes them Happy Birthday on their birthday.
In "Why develop skills with Alexa?" You saw what happens when a user interacts with a simple skill called "Hello World". In the video below, let's take a look at how users will interact with Cake Walk once you've built it:
As you can see the skill is simple to use yet a bit complex to build. The burden is on us, the skill builder, to make the interaction simple and natural. One way to make it as natural as possible is to mimic human conversational patterns. Humans have memory so your skill should too. It would be frustrating if your best friend always had to ask your name (which may be a sign that they really aren't your best friend at all). While you could build cake walk in a day, because of its complexity you'll build cake walk over four modules in this course.
Once you've completed this course; you'll have built a skill that is useful, simple, and sticky. Useful skills provide value to users. For this skill Cake Walk is fun and useful to users by celebrating their birthday with a count down. Cake Walk is also a great example of a sticky skill, which retains the user's interest and inspires them to keep coming back. Cake Walk encourages our user to keep checking in until their special day. Let's get started!
If this is your first time building an Alexa skill, we recommend completing this module and the next three, which walk you through all the necessary steps.
Don't worry if you get stuck along the way or if your code breaks. At the end of each module, the complete working code solution is provided for you under the Code heading.
If you're already up to speed on the fundamentals of Alexa skill building and want to make your skill more conversational, please take a look at the conversational design course.
a. Click Create Skill on the right-hand side of the console. A new page displays.
b. In the Skill name field, enter Cake Walk.
c. Leave the Default language set to English (US).
d. You are building a custom skill. Under Choose a model to add to your skill, select Custom.
Skills have a front end and backend. The front end is where you map utterances (what the user says) into an intent (the desired action). You must decide how to handle the user's intent in the backend. Host the skill yourself using an AWS Lambda function or HTTPS endpoint, or choose Alexa to host the skill for you. There are limits to the AWS Free Tier, so if your skill goes viral, you may want to move to the self-hosted option. For this course, use Alexa-Hosted.
The first thing a user will want to do with the skill is open it. The intent of opening the skill is built into the experience, so you don't need to define this intent in your front end.
However, you need to respond to the intent in your backend. In this step, you will update your backend code to greet the user when they open the skill.
a. Open the Cake Walk skill in the Alexa developer console. Click the Code tab. The code editor opens the index.js file.
You will use the ASK SDK for Node.js module. To define how your skill responds to a JSON request, you will define a handler for each intent.
There are two pieces to a handler:
The canHandle() function is where you define what requests the handler responds to. The handle() function returns a response to the user.
If your skill receives a request, the canHandle() function within each handler determines whether or not that handler can service the request.
In this case, the user wants to launch the skill, which is a LaunchRequest. Therefore, the canHandle() function within the LaunchRequestHandler will let the SDK know it can fulfill the request. In computer terms, the canHandle returns true to confirm it can do the work.
Tip: In the code editor, search for text by pressing CTRL+F (Command+F on a Mac). A search window opens. This is helpful for searching for pieces of code within the editor.
What should happen when a user launches the Cake Walk skill? In this case, you want the skill to simply confirm that the user opened it by saying, "Hello! Welcome to Cake Walk. That was a piece of cake! Bye!"
Within the LaunchRequestHandler object, find the handle() function. This function uses the responseBuilder function to compose and return the response to the user.
Within the handle() function, find the line that begins const speechText. This variable contains the string of words the skill should say back to the user when they launch the skill. Let's change what it says to make sense for this skill.
b. Within the LaunchRequestHandler object, find the handle() function, and the line that begins const speechText. Replace that line with the following:
const speechText = 'Hello! Welcome to Cake Walk. That was a piece of cake! Bye!';
Be sure to include the semicolon (;) at the end of the line.
If you are not familiar with programming, a string is encapsulated in single or double quotation marks. To change a string's text, replace the text within the quotation marks.
Within the LaunchRequestHandler, on the line under the speech text you just replaced, look for handlerInput.responseBuilder. This piece of the SDK will help build the response to the user.
On the next line, look for .speak(speechText). Note the speechText variable, which you defined earlier. Calling the .speak() function tells responseBuilder to speak the value of speechText to the user.
Next, look for the .reprompt() function within responseBuilder. (Be sure you are looking in the LaunchRequestHandler, within the handle() function.)
If the skill was supposed to listen for the user's response, you would use this. In this case, you want the skill to speak and then exit. Therefore, let's omit this line of code for now.
c. Within the LaunchRequestHandler, in the handle() function, find the line that begins .reprompt(). Add a double forward slash (//) at the beginning of the line. This turns the line into a comment, meaning the line is ignored when the code runs.
d. Next, look for the .getResponse() function just below the line you commented out in the LaunchRequestHandler. This converts the responseBuilder's work into the response that the skill will return. Remember the line that started with return? Think of it like hitting the Send button—it sends the response.
After making all of these changes, your code in the handle() function within the LaunchRequestHandler should look like the following:
You have built the code that will handle a LaunchRequest for this skill. Before doing anything else, save your changes and deploy the code.
There are two ways to test your skill in the console. With the first method, type what the user would say into the box at the top left. Be precise—spelling matters! Alternately, speak to the skill by clicking and holding the microphone icon and speaking.
So far, the skill has one intent: LaunchRequest. This function responds to the user when they ask Alexa to open or launch the skill. The user will say, "Alexa, open Cake Walk." Cake Walk is the name of your skill and was automatically set as the invocation name for the skill. You can change the invocation name, but let's leave it as is for this exercise.
When testing your skill in the Alexa developer console, you don't need to provide the wake word (usually "Alexa"). Typing or saying, "Open Cake Walk" is fine. When testing on an Alexa-enabled device, you need the wake word: "Alexa, open Cake Walk."
When you open the skill, does it say, “Hello! Welcome to Cake Walk. That was a piece of cake! Bye!”? If so, congratulations! You have laid the groundwork for the skill. You will be building new skills with compelling conversational voice experiences in no time.
There is still a lot to learn! In the next section, you will expand the skill to make it more useful.
If your skill isn't working or you're getting some kind of syntax error, download the following working code sample. Go to the Code tab in the Alexa developer console and copy and paste the code into the index.js file. Be sure to save and deploy the code before testing it.