conv.data lost in followup intent in DialogFlow - node.js

Question

I'm using node.js 8 runtime in my Google Cloud function, attached to my DialogFlow app (V2 API).
I can use conv.data to store temporary data within the current conversation. Unfortunately, conv.data does not seem to retain data after a followup intent.
For example, in my intent the following code:
conv.data.result = "Hello!";
console.log("[DEBUG] conv.data.result = "+conv.data.result);
conv.followup("customEvent1");
produces the following log:
[DEBUG] conv.data.result = Hello!
This is my followup intent:
app.intent('CUSTOM_EVENT_INTENT', (conv) => {
console.log("[DEBUG] - CUSTOM_EVENT_INTENT");
console.log("[DEBUG] - conv.data.result = "+conv.data.result);
if(!conv.data.result) {
console.log("[DEBUG] - I give up");
conv.close("Nessuna risposta");
}
else conv.ask(conv.data.result);
});
which produces the following log:
[DEBUG] - conv.data.result = undefined
[DEBUG] - I give up
Looks like I'm missing something very important in followup intents...
Thanks,
Roberto

Answer 1

I would suggest using context instead of data. Context has few more advantages over data objects. It can be accessible in multiple dialog and intents.
function getParamFromContext(key){
// get the value set earlier in the context
let globalContext = agent.context.get('global_main_context');
return globalContext.parameters[key];
}
function updateGlobalContext(agent, key, value) {
// create a global method to maintain all required data within conversation
let globalContext = agent.context.get('global_main_context');
let param = globalContext ? globalContext.parameters : {};
param[key] = value;
agent.context.set({
name: 'global_main_context',
lifespan: 5,
parameters: param
});
}
Call the method within a conversation with agent object.
in app.js
intentMap.set("Size Intent", setSize);
function setSize(){
let size = agent.parameters.size;
updateShippingObjectContext(agent, 'size', size);
}

Answer 2

I think you're talking about Followup Events rather than Followup Intents. Followup Intents are set as Intents that may be triggered after an Intent has by the user doing some action - this is done by setting a Context. Followup Events are set during fulfillment and are intended to trigger an Intent that has this Event set.
In most cases, you don't need to use Followup Events.
Instead - just call a function that does the processing and replies how you want it to do. There is nothing saying that your Handler function has to do everything itself - it can call a function just like any other function, and can call it with parameters.
So it is perfectly reasonable to have Intent Handlers like
app.intent('intent.one', (conv) => {
reply( conv, "Hello!" );
});
app.intent('intent.two', (conv) => {
reply( conv, "How are you?" );
});
app.intent('intent.quit', (conv) => {
reply( conv );
});
function reply( conv, msg ){
if( !msg ){
conv.close( "I give up!" );
} else {
cov.ask( msg );
}
}
That still doesn't explain why it didn't work.
What you are "missing" with how you use Followup Events is that using conv.followup() does not send anything that you may have sent back to Dialogflow when it redirects to the Event. As the documentation says:
Triggers an intent of your choosing by sending a followup event from the webhook. [...] Dialogflow will not pass anything back to Google Assistant, therefore Google Assistant specific information, most notably conv.user.storage, is ignored.
What you can do, however, is send parameters to the new Intent that is detected from the Event. Something like this might work:
const params = {
result: "Hello!"
};
conv.followup("customEvent1", params);
and then in the handler for the event's Intent:
app.intent('CUSTOM_EVENT_INTENT', (conv) => {
console.log("[DEBUG] - CUSTOM_EVENT_INTENT");
console.log("[DEBUG] - conv.parameters.result = "+conv.parameters.result);
if(!conv.parameters.result) {
console.log("[DEBUG] - I give up");
conv.close("Nessuna risposta");
}
else conv.ask(conv.parameters.result);
});