$fields→changedType()

You can add your own hook events that are executed either before or after the $fields->changedType(…) method is executed. Examples of both are included below. A good place for hook code such as this is in your /site/ready.php file.

Hooking before

The 'before' hooks are called immediately before each $fields->changedType(…) method call is executed. This type of hook is especially useful for modifying arguments before they are sent to the method.

$this->addHookBefore('Fields::changedType', function(HookEvent $event) {
  // Get the object the event occurred on, if needed
  $fields = $event->object;

  // Get values of arguments sent to hook (and optionally modify them)
  $item = $event->arguments(0);
  $fromType = $event->arguments(1);
  $toType = $event->arguments(2);

  /* Your code here, perhaps modifying arguments */

  // Populate back arguments (if you have modified them)
  $event->arguments(0, $item);
  $event->arguments(1, $fromType);
  $event->arguments(2, $toType);
});

Hooking after

The 'after' hooks are called immediately after each $fields->changedType(…) method call is executed. This type of hook is especially useful for modifying the value that was returned by the method call.

$this->addHookAfter('Fields::changedType', function(HookEvent $event) {
  // Get the object the event occurred on, if needed
  $fields = $event->object;

  // An 'after' hook can retrieve and/or modify the return value
  $return = $event->return;

  // Get values of arguments sent to hook (if needed)
  $item = $event->arguments(0);
  $fromType = $event->arguments(1);
  $toType = $event->arguments(2);

  /* Your code here, perhaps modifying the return value */

  // Populate back return value, if you have modified it
  $event->return = $return;
});