Nested Routers - Creating conversation blocks

Developing large chatbots with many flows requires advanced code organization. We came up with solution which allows:

  • creating reusable conversation blocks
  • composability of whole flows
  • keeping code clear and maintainable

Basic concept

Each conversation block has a single entry point and one or more exit points.

  start
    |
  |-O------------|
  |              |
  | conversation |      is represented by single
  |     block    |      <Router> instance
  |              |
  |-X---X---X----|
    |   |   |

    exit points

When attaching the block into application, each exit point must be "connected" into a parent conversation block.

Example

First, let's start with a module. There is a single entry point: ('/') and two exit points ('setName' and 'leave'). It's recomended to return data instead of setting them to state.

// setName.js
const { Router } = require('wingbot');

const bot = new Router();

// entry point
bot.use('/', (req, res) => {
    res.text('Please, give me a full name :)')
        .expected('name');
});

// leave exit point
bot.use('/leave', () => Router.exit('leave'));

bot.use('/name', (req, res) => {
    const name = req.text();
    if (!name || name.split(' ').length < 2) {
        res.text('Fullname must have two words or more.')
            .text('Please try it again', {
                leave: 'Don\'t want'
            });
        // just stop dispatching (equal to "return undefined;")
        return Router.END;
    }
    // pass data to exit point
    return Router.exit('setName', { name });
});

module.exports = bot;

And here is how to connect the block into the application. All exit points must be covered by handlers: .onExit() to ensure continuous conversation.

// index.js
const { Router, Settings } = require('wingbot');
const setName = require('./setName');

const settings = new Settings('pagetoken');
settings.getStartedButton('/start');

const bot = new Router();

bot.use('/start', (req, res) => {
    if (req.state.name) {
        res.text(`Hello, I'am ${req.state.name}`, {
            setName: 'That\'s bad name'
        });
    } else {
        res.text('Hello, please give me name!', {
            setName: 'Let\'s do it'
        });
    }
});

bot.use('/setName', setName)
    // react on setName exit point
    .onExit('setName', ({ name }, req, res, postBack) => {
        res.setState({ name });
        postBack('/');
    })
    // react on leave exit point
    .onExit('leave', (data, req, res, postBack) => postBack('/start'));

module.exports = bot;

And this is, how the implementation works:

*-----------------------------------*
|                       Get started |
| Hello, please give me name!       |
|                                   |
|                      Let\'s do it |
| Please, give me a full name :)    |
|                                   |
|                                Ok |
| Fullname must have two words      |
| or more.                          |
| Please try it again               |
|                                   |
|                       Dorian Gray |
| Hello, I'am Dorian Gray           |
*-----------------------------------*

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