How do I best modularize dialogs with Microsoft Bot Framework (v3)? - node.js

Question

I've just been given a project where I'll need to learn and deal with Microsoft Bot Framework, version 3.2 (it's an old project that I'm modifying).
I'm working through the examples and trying to understand how dialog flow works, and how I might best modularize it.
As I understand it, when you create your bot like this
// CODE SAMPLE 1
const bot = new builder.UniversalBot(connector, [
function (session) {
session.send("Welcome to the dinner reservation.");
session.beginDialog('askForDateTime');
},
/*
functions omitted for brevity
*/
]).set('storage', inMemoryStorage); // Register in-memory storage
the array of functions that comprise your "default dialog" must be given when the bot is created -- that is, you can't add the default dialog at a later point, or change it. Is that correct?
Then, later, if you want to modularize your dialog structure, you can have something like this (referring to the code above)
// CODE SAMPLE 2 (in same file as code above)
bot.dialog('askForDateTime', [
function (session) {
builder.Prompts.time(session, "Please provide a reservation date and time (e.g.: June 6th at 5pm)");
},
function (session, results) {
session.endDialogWithResult(results);
}
]);
So, is bot.dialog registering this dialog with the bot for later use? That is, there's a look-up of some sort at run-time -- during the conversation -- based on this string that connects session.beginDialog('askForDateTime'); in the first code sample with the functions registered with bot.dialog('askForDateTime') in the second code sample?
When I looked at the SDK reference, I see that beginDialog accepts an IAddress
function beginDialog(address: IAddress, dialogId: string, dialogArgs?: any, done?: (err: Error) => void)
where it says
Address routing information for an event. Addresses are bidirectional
meaning they can be used to address both incoming and outgoing events.
They're also connector specific meaning that connectors are free to
add their own fields to the address.
So this 'registration' via string is basically an event registration system, kind of like addEventListener, but in this case it's not registering an action per se, but a dialog?
Two last questions:
Can one call session.beginDialog from within a bot.dialog? That is, have a nested tree of dialogs? As it is, the only example is of nesting from the default dialog, but I didn't know if it could go deeper.
Finally, how can one modularize your dialogs into separate node modules, that is, move your sub-dialogs into separate files? I thought of something like this:
// askForDateTime.js
module.exports = bot =>
bot.dialog('askForDateTime', [
function (session) {
builder.Prompts.time(session, "Please provide a reservation date and time (e.g.: June 6th at 5pm)");
},
function (session, results) {
session.endDialogWithResult(results);
}
]);
but don't see how to use it in my main app
// app.js
const askDateTimeDialog = require('./askForDateTime')(bot) // how to use this? I need to pass in a bot that's not yet created. Do I even need to import it?
const bot = new builder.UniversalBot(connector, [
function (session) {
session.send("Welcome to the dinner reservation.");
session.beginDialog('askForDateTime'); // <--- how to beginDialog with imported dialog? Or is the 'registration' behind the scenes sufficient since I'm just using the same string?
},
/*
functions omitted for brevity
*/
]).set('storage', inMemoryStorage); // Register in-memory storage
Thanks for any help! I realize this probably all is easier with version 4, but I need to use an earlier version.

Answer 1

First and foremost, please be aware the Botbuilder V3 is in sunset with support ending at the end of 2019. You can read more about this topic here and options for migrating from v3 to v4 here.
Regarding default dialogs, the other method is to only pass the connector into the adapter and then start a dialog when the conversationUpdate occurs. There are some challenges that can bubble up when using conversationUpdate, so I would look over this blog post before continuing.
var bot = new builder.UniversalBot(connector)
bot.on('conversationUpdate', function (message) {
if (message.membersAdded) {
message.membersAdded.forEach(function (identity) {
if (identity.id === message.address.bot.id) {
bot.beginDialog(message.address, '/main');
}
});
}
});
// ----greetings.js -----
bot.dialog('/main', [
function (session, args, next) {
session.send("Glad you could join.");
session.beginDialog('/nextDialog');
}
]);
Regarding beginDialog() registration/addressing, there is no pre-registeration that occurs. When a dialog is called, it's essentially called like any other function is. The address, more or less, is used for managing dialog state (i.e. where a bot is in a conversation) - whether a dialog is being added to stack, is in use, or being popped off the stack.
Regarding calling one dialog within another, yes it is doable, as you can see in this sample:
lib.dialog('/', [
[...other functions...]
function (session, args) {
session.dialogData.recipientPhoneNumber = args.response;
session.beginDialog('validators:notes', {
prompt: session.gettext('ask_note'),
retryPrompt: session.gettext('invalid_note')
});
},
[...other functions...]
]);
Lastly, regarding modularizing, yes, this is also doable. Look over either of these two samples. core-MultiDialogs is the less complicated but demo-ContosoFlowers is also a good example to reference.
Hope of help!