Cannot read property 'parameters' of undefined while passing Context - Actions on Google - dialogflow-es

Question

Currently I am trying to develop an action.
I am trying to achieve to reuse an intent. Concretely said, it means that the Assistant shall give me the first three items of a list and if I ask for more, then it should give me the next three items of the list.
I implemented the logic, which is locally working but sadly I always got the first three items from the list. Therefore i tried using a context, where I want to pass the index as a parameter and here i am running into the problem. The cloud function logs always gives me:
Cannot read property 'parameters' of undefined.
I am using dialog v2 api and the actions on Google sdk. Following link provides an example how to implement the context and I don't see a big difference there. https://developers.google.com/actions/reference/nodejsv2/overview
The code written for it looks like this:
app.intent('Default Welcome Intent', conv => {
conv.ask('Welcome.')
const lifespan = 100;
const parameters = {
index: 0,
};
conv.contexts.set('movieCtx', lifespan, parameters);
});
app.intent('New Cinema Movies Intent', async conv => {
let movieCtx = conv.contexts.get('movieCtx');
let index = movieCtx.parameters[index]
let movieRepository = new MovieRepository();
movieRepository.index = index;
await movieRepository.fetchNextTitle(3).then(function(titles) {
movieCtx.parameters[index] = movieRepository.index;
conv.ask('The 3 movies are:' + titles.join(', '))
return true;
}).catch(function(err) {
console.log(err);
return false;
});
})
My dependencies:
{
"name": "functions",
"description": "Cloud Functions for Firebase",
"scripts": {
"lint": "eslint .",
"serve": "firebase serve --only functions",
"shell": "firebase functions:shell",
"start": "npm run shell",
"deploy": "firebase deploy --only functions",
"logs": "firebase functions:log"
},
"dependencies": {
"actions-on-google": "^2.5.0",
"firebase-admin": "~6.0.0",
"firebase-functions": "^2.0.3",
"pg": "^7.7.1"
},
"devDependencies": {
"eslint": "^4.12.0",
"eslint-plugin-promise": "^3.6.0"
},
"private": true
}
Update:
I also tried to change the following lines but also that couldn't help me:
const parameters = {
movieIndex: 0,
};
let index = movieCtx.parameters['movieIndex']

Answer 1

The line
let index = movieCtx.parameters[index]
Should probably be
let index = movieCtx.parameters['index']
(You don't have index defined previous to that, so it is trying to get the reference of undefined, which isn't valid.)

Answer 2

I was able to find the answer!
const {dialogflow} = require('actions-on-google');
const functions = require('firebase-functions');
const MovieRepository = require('./PostgreSQL/MovieRepository');
let movieRepository = new MovieRepository();
const app = dialogflow({debug: true});
const AppContexts = {
NUMBER: 'number',
}
app.intent('Default Welcome Intent', (conv) => {
const lifespan = 10;
const parameters = {
movieIndex: 0,
};
conv.contexts.set(AppContexts.NUMBER, lifespan, parameters);
conv.ask('Welcome!')
});
app.intent('New Cinema Movies Intent', async (conv) => {
const movieCtx = conv.contexts.get(AppContexts.NUMBER);
await movieRepository.fetchNextTitle(3).then(function(titles) {
movieCtx.parameters.movieIndex = movieRepository.index;
conv.ask('The 3 movie titles are: ' + titles.join(', '));
return true;
}).catch(function(err) {
console.log(err);
return false;
});
})
app.intent('Default Fallback Intent', conv => {
conv.ask('Sorry. Can you repeat?')
})
exports.dialogflowFirebaseFulfillment = functions.https.onRequest(app);
As you can see you have to create the AppContext above the intents. Somhow weird but important is that you apply
NUMBER: 'number'
to the context, otherwise you get an undefined context again. And to access your parameters you just need to append your the value of your parameter like this:
movieCtx.parameters.movieIndex