Triggering event on input/select value change with Spring web flow - spring

Question

I wanna trigger flow change when user change the value in select box:
<select>
<options>
<option>1</option>
<option>2</option>
</options>
</select>
After reading this docs: https://docs.spring.io/spring-webflow/docs/current/reference/html/spring-mvc.html#spring-mvc-resuming-on-event
I did not find the answer.
Please can any one help? Any advice appreciated.
The change I wanna achieve is to set button to be activated, when value has been chosen from select box.

Answer 1

there are 2 ways to do this:
First, using strictly javascript (all in the UI), by using onchange and/or onclick on your select element to find the button and activate/deactivate it
Second, using Webflow:
submit the form on onchange
re-render the view with the proper changes
Assuming you want to go with webflow here, you can use this:
JSP
<form id="myFormId" action="${flowExecutionUrl}" method="post">
<select id="mySelectId" onchange="Spring.remoting.submitForm('mySelectId', 'myFormId', {fragments:'body', _eventId: 'myChangeEvent'}); return false;">
...
</select>
</form>
Flow
<view-state id="myViewStateId">
<transition on="myChangeEvent" validate="false" bind="true">
<!-- change some property to enable your button -->
</transition>
</view-state>
This will re-render the view and the property/attribute you are using to enable/disable your button will be updated.
It is important to use validate="false" otherwise validation error(s) could prevent your transition from succeeding