Start an Action Chain When a Variable Changes

You can start an action chain when the value stored in a variable changes by adding an onValueChanged event to the variable.

When you use an onValueChanged event to trigger an action chain, the trigger has the payload of the variable's old and new values. For example, let's say you changed an employee's Name property and reset the Employee; the framework sends an event that the Employee has changed, and as part of the payload, indicates that the name has changed.

To start an action chain when the value of a variable changes:

1. Open an artifact's Variables editor.
2. Select the variable in the list, then click Events in the Properties pane.
3. Click + Event Listener.
4. Select an action chain from the list and click Select.

   When you add the event to the variable, a listener that listens for the onValueChanged event on the variable is automatically created. The variable's Events tab in the Properties pane displays the action chain the event listener starts; you can change or remove the action chain, assign input parameters, and add more action chains.
   
   Description of the illustration event-listener-variable.png
   

   Note:

   Variable events and event listeners are not listed in an artifact's Events or Event Listeners tabs.