I've got a function I want to run on page save/ publish if certain custom CMS fields have been changed.

For example:

class Foo extends DataObjectDecorator {
 public function updateCMSFields() {
  $fields->addFieldsToTab("Root.Content", array(
   new NumericField('Bar', 'Change me and save this page to trigger FooBar function')
  ));
 }
}

function FooBar(){
 //Do things
 //With stuff
}

Any ideas?

create some custom javascript to handle the change (inspect the current form to get the required ID to watch), add a REquirements::javascript within the function - job done.

Hi Swaiba

Thank you for that.

I understand the principle of what you're saying but struggling with the correct execution.

Do you have any code examples of how to do this?

Cheers
Tama

Looking at the SiteTree::onBeforeWrite() function I noticed the use of $this->isChanged('URLSegment') (line 1339). So maybe this would work in your Page class:

protected function onBeforeWrite() {

	if ($this->isChanged('SomeField')){
		// do something
	}

	parent::onBeforeWrite();
}

Mind - I didn't test it...