Bottender Actions

Bottender actions are the smallest building blocks of Bottender apps. An action describes what you want your bot to do when receiving an event:

async function SayHi(context) {
  await context.sendText('Hi!');
}

A typical action takes context as the first argument. The context variable provides the data in the conversation context and various methods to interact with the user. You can use those data and methods to build your actions. For example, you may create an Echo action to reply with the text it receives to the user using context.sendText(context.event.text):

async function Echo(context) {
  if (context.event.isText) {
    await context.sendText(context.event.text);
  }
}

Note: The context variable provides methods differently among platforms. You can apply a progressive enhancement strategy using platform-specific methods.

Composing Actions

Bottender actions are composable. Actions can refer to other actions as their return value.

For example, you may use the SayHi and Unknown action to create another App action:

async function SayHi(context) {
  await context.sendText('Hi!');
}

async function Unknown(context) {
  await context.sendText('Sorry.');
}

async function App(context) {
  if (context.event.text == 'hi') {
    return SayHi;
  }
  return Unknown;
}

If the App action receives a "hi" text message, it replies with a "Hi!" text message. Otherwise, the App action replies with a "Sorry." text message.

Note: New Bottender apps created by Create Bottender App have an App action as an entry point in the src/index.js file. However, if you are familiar with Bottender, you may rename the action or even use different structure instead.

Passing Props to Actions

In the above examples, the actions only take one argument context. However, you can utilize the second argument - props to define your actions with flexibility in mind:

async function SayHi(context, props) {
  await context.sendText(`Hi, ${props.name}.`);
}

Instead of returning the action directly without props, you can use the withProps function to provide an object as props for the action:

const { withProps } = require('bottender');

async function App(context) {
  return withProps(SayHi, { name: 'Bob' });
}

Bottender provides { name: 'Bob' } as props for the SayHi action, so your bot replies the "Hi, Bob." text message as a result to the user.

How to Debug Actions

Bottender uses the famous debug package internally to collect some helpful information that can be showed up when you provide the corresponding DEBUG environment variable. To debug your actions, you may run your command with DEBUG=bottender:action, for example:

DEBUG=bottender:action npm start

Note: If you are developing your bots on Windows, you may use the cross-env package to assign the DEBUG environment variable:

cross-env DEBUG=bottender:action npm start

Or you may put your DEBUG environment setting into your .env file:

DEBUG=bottender:action

We recommend that you always name your actions, so Bottender prints meaningful paths for you to debug instead of showing Anonymous as the action name.