HTTP request failing in AWS Lambda function for Alexa - node.js

Question

I am trying to return data from an external api in my inline Lambda function but when I test this in the developer console for Alexa, I get 'There was a problem with the requested skills response' and I can't work out why.
Also, as I am doing this from the AWS console, I can't console.log to see what it actually being returned.
(I have removed the default intents for the sake of the post)
const request = require('request');
const handlers = {
'LaunchRequest': function () {
this.emit(':ask', 'Welcome');
},
'GiveUpdateIntent': function (){
var slot = this.event.request.intent.slots.line.value;
httpGet(slot, (theResult) => {
this.response.speak(theResult);
this.emit(':responseReady');
});
}
};
function httpGet(query, callback) {
var options = {
host: 'api.tfl.gov.uk',
path: '/line/' + encodeURIComponent(query) + '/status',
method: 'GET',
};
var req = http.request(options, res => {
res.setEncoding('utf8');
var responseString = "";
//accept incoming data asynchronously
res.on('data', chunk => {
responseString += chunk;
});
//return the data when streaming is complete
res.on('end', () => {
console.log(responseString[0]);
callback(responseString[0]);
});
});
req.end();
}
exports.handler = function (event, context, callback) {
const alexa = Alexa.handler(event, context, callback);
alexa.APP_ID = APP_ID;
alexa.registerHandlers(handlers);
alexa.execute();
};

Answer 1

"There was a problem with the requested skills response" generally means that the response from your skill was not in the expected format.
Your API request
Ex: vicotria
https://api.tfl.gov.uk/Line/victoria/Status
returns a JSON, and you can't directly pass it Alexa as response. Before you send it back to Alexa, take out status that you actually want Alexa to speak. Then put that into a meaningful sentence that any skill user will understand and send it back.
For example you can return something like:
var speech = "Status severity description for " +
this.event.request.intent.slots.line.value +
" is "
+ responseBody[0].lineStatuses.statusSeverityDescription;
this.emit(':ask',speech, "your re-prompt here");
This is a sample JSON that I got
[
{
"$type": "Tfl.Api.Presentation.Entities.Line, Tfl.Api.Presentation.Entities",
"id": "victoria",
"name": "Victoria",
"modeName": "tube",
"disruptions": [],
"created": "2018-07-31T12:11:08.477Z",
"modified": "2018-07-31T12:11:08.477Z",
"lineStatuses": [
{
"$type": "Tfl.Api.Presentation.Entities.LineStatus, Tfl.Api.Presentation.Entities",
"id": 0,
"statusSeverity": 10,
"statusSeverityDescription": "Good Service",
"created": "0001-01-01T00:00:00",
"validityPeriods": []
}
],
"routeSections": [],
"serviceTypes": [
{
"$type": "Tfl.Api.Presentation.Entities.LineServiceTypeInfo, Tfl.Api.Presentation.Entities",
"name": "Regular",
"uri": "/Line/Route?ids=Victoria&serviceTypes=Regular"
},
{
"$type": "Tfl.Api.Presentation.Entities.LineServiceTypeInfo, Tfl.Api.Presentation.Entities",
"name": "Night",
"uri": "/Line/Route?ids=Victoria&serviceTypes=Night"
}
],
"crowding": {
"$type": "Tfl.Api.Presentation.Entities.Crowding, Tfl.Api.Presentation.Entities"
}
}
]
CloudWatch:
Always make use of CloudWatch to see the logs of your Lambda function, you will get a link under Monitoring tab of your Lambda Function.
Configuring Lambda Test Events: You can test you Lambda code right from your inline editor by configuring Lambda Test Events under Test menu of your inline editor. A function can have up to 10 test events.

Answer 2

This is because your handler is returning before the callback is called. I strongly suggest to move away from callback based development in NodeJS and to use Promise instead.
I just answered a similar question, and provided sample code with promises. Check it here How to make an asynchronous api call for Alexa Skill application with a Lambda function?

Answer 3

The issue turned out to be with using http itself instead of https.
The only response back that I was getting was a status code of 302 which is a redirection because the api I was calling changes all http requests to https.
Therefore, I changed my import to https and used the https.get method (instead of http.get) to call the api and the correct response was returned.