events.md

Events

Just like middlewares are for all communications between the external world and your bot, Events are for all internal and inter-modules communications.

Events are sent and listened on by botpress's EventBus, which is just like a regular EventEmitter except that events are distributed in real-time to all listeners on the server-side and the client-side through websockets. This means that you can emit events in your React code and capture them in the module's node codebase.

When developping a module, it is considered good practice to emit events for the various tasks it does.

Example

Module /src/index.js

module.exports = {
  init: function(bp) {},
  ready: function(bp) {
    bp.events.on('test.clicked', data => {
      bp.logger.debug('[EVENT TEST]', data)
    })
  }
}

module /src/views/index.jsx

import React from 'react'

export default class TemplateModule extends React.Component {

 emitEvent() {
   this.props.bp.events.emit('test.clicked', { a: '123' })
 }

 render() {
   return <button onClick={::this.emitEvent}>Click me</button>
 }
}

When not to use Events

You should not use Events for exposing features or for information retrieval. For this, you should usually setup an API instead as it has several obvious advantages over events.