In rules you have the ability to check whether a field in a form has been changed by negating node-unchanged:field-xyz = 123.

I want to check whether a field has changed programmatically with the $form and $form_state.

How would you do this?

  • Hey hey, what have you tried so far? And what is your exact question? Please update your post to provide specific problems we can help you to solve.
    – leymannx
    Jan 22, 2018 at 20:03
  • Compare the $form default value vs the $form_state value. If they are not equal, then there was a change. You'll want to do this inside a custom form validate or submit function. Use hook_form_alter to add your custom validate or submit function. See: Custom validation for a form? as an example.
    – No Sssweat
    Jan 23, 2018 at 1:50


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