Catch-Alls

Xip Catch-Alls are designed to handle the error cases within bots. Either the bot doesn't understand what a user typed or an error occurred. If this were a webpage, we'd see the dreaded HTTP 500 error page.

Catch-Alls are designed to move beyond simple "I don't understand" messages and help users get back on track. The better your CatchAlls, the better your bot.

Triggering

The catch_all flow is automatically triggered when either of two things happens within a controller action:

1. The action fails to progress a user.

2. An Exception is raised.

Multi-Level

Xip keeps track of how many times a Catch-All is triggered for a given session. This allows you to build experiences in which the user is provided different responses for subsequent failures.

So for example, if in the hello flow and say_hello state an exception is raised, then Catch-All Level 1 will be called. If the user is return to that same flow and state and another exception is raised, Catch-All Level 2 will be called. This continues until you either run out of Catch-All states or if the Catch-All counter resets.

Retrying

By default, a Xip bot comes with Catch-All Level 1 already defined. Here is the default CatchAllsController and associated reply:

class CatchAllsController < BotController
​
  def level1
    send_replies
​
    if fail_session.present?
      step_to session: fail_session
    else
      step_to session: previous_session - 2.states
    end
  end
​
private
​
   def fail_session
     previous_session.flow.current_state.fails_to
   end
​
end

- reply_type: text
  text: Oops. It looks like something went wrong. Let's try that again

In the controller action, we check if the previous_session (the one that failed) specified a fails_to state. If so, we send the user there. Otherwise, we send the user back 2 states.

Sending a user back two states is a pretty good generic action. Going back 1 state takes us back to the action that failed. Since the actions most likely to fail are get actions, or actions that deal with user responses, going back 2 states usually takes us back to the original "question".

Adding More Levels

If you would like to extend the experience, add a level2 controller action and associated reply (and update the FlowMap). You can go as far as you want. CatchAlls have no limit, just make sure you increment using the standardized method names of level1, level2, level3, level4, etc.

If a user has encountered the maximum number of CatchAll levels that have been defined, it won't attempt to call any more levels.

Catch-All Reasons

As mentioned in the Triggering section above, there are two reasons a Catch-All triggers. Xip will provide the CatchAllsController with that reason so you can customize your messages and take the appropriate action.

So if for example your bot just didn't recognize the message sent by the user, you may ask the user to repeat. If however, your database is down, you might other action.

Here is an example usage:

class CatchAllsController < BotController
  
  before_action :set_catch_all_reason
​
  def level1
    send_catch_all_replies('level1')
​
    if fail_session.present?
      step_to session: fail_session, pos: -1
    else
      step_to session: previous_session - 2.states, pos: -1
    end
  end
​
  def level2
    send_catch_all_replies('level2')
  end
​
  def level3
    send_catch_all_replies('level3')
  end
​
  private
​
  def fail_session
    previous_session.flow.current_state.fails_to
  end
​
  def send_catch_all_replies(level)
    if @reason == :unrecognized_message
      send_replies(custom_reply: "catch_alls/#{level}_unrecognized")
    else
      send_replies(custom_reply: "catch_alls/#{level}")
    end
  end
​
  def set_catch_all_reason
    @reason = case current_message.catch_all_reason[:err].to_s
    when 'Xip::Errors::UnrecognizedMessage'
      :unrecognized_message
    else
      :system_error
    end
  end
​
end
​

In this CatchAllsController we have two sets of Catch-All replies. One for when the message was unrecognized and another for when we've encountered a system error. We dynamically send the appropriate reply based on the @reason instance variable that we set with the before_action in the controller.