Bind context and other arguments to your alexa-sdk handlers using a functional approach.
- Use pure functions as handlers.
- Pass extra arguments.
- Bind the context into your handlers.
- Bind the context into the extra arguments.
npm i alexa-connect-handlers --save
alexa-connect-handlers consist on two basic functions, mapToHandlers and connect depending on your solution you might need both or just one of them.
mapToHandlers accepts your handlers object as the first argument and an object as the second argument, this function will bind your properties to the context so you can use them inside your handlers and/or extra arguments, I mainly wrote this function to pass properties before registering your handlers, eg.
import Alexa from 'alexa-sdk';
import { mapToHandlers } from 'alexa-connect-handlers';
import handlers from './handlers';
import RestClient from './RestClient'; // We want to bind an instance of this class to our hanlders context.
exports.handler = (event, context) => {
const alexa = Alexa.handler(event, context);
// We create the instance of the class here.
const client = new RestClient({
tokenType: 'Bearer',
accessToken: 'eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9',
});
// this is where we bind the instance to our handlers.
alexa.registerHandlers(mapToHandlers(handlers, { client }));
alexa.execute();
};Wrap your handler using the Higher-Order function connect to bind the context to the first argument of the function, you can invoke alexa-sdk properties from here like response, emit, attributes, t.
Pass as a second argument of connect an object with the properties that you want to pass to your handler, extra arguments will be available on the second argument of your function ({ emit }, { myExtraArgument }).
import connect from 'alexa-connect-handlers';
const AmazonNextIntent => ({ response, emit }) => {
response.speak('Hello World');
return emit(':responseReady');
}
export default connect(AmazonNextIntent)You can pass an object as extra arguments and this will be available as the second argument of our handlers.
import connect from 'alexa-connect-handlers';
const AmazonNextIntent => ({ response, emit }, { foo }) => {
response.speak(`Hello World my name is ${foo}`);
return emit(':responseReady');
}
export default connect(AmazonNextIntent, { foo: 'bar' })You can pass a function inside our extra arguments object and the context will be available on the first argument of the inner function, you can find and example of this below.
import connect from 'alexa-connect-handlers';
// Brings the context from the connected function
// This is extremely useful for calling an instance of a class.
const ymcaSpreader = () => ({ ymca }) => ymca.split('').join(' ');
const AmazonNextIntent => ({ response, emit }, { ymca, ymcaSpreader }) => {
response.speak(`It's fun to stay at the ${ymcaSpreader()}`);
return emit(':responseReady');
}
export default connect(AmazonNextIntent, { ymca: 'ymca', ymcaSpreader })