Change field "Only visible if..." through API

[iipa]

Hi!

I have two Page Reference fields: Category and Subcategory. Category is parent of Subcategory, and can have 0 to n Subcategories. Fields are selected by dropdown selection.

I'm trying to achieve following logic:

1. Select Category (obviously works)

2. Change Subcategory options based on selected Category (this works)

3. Hide the Subcategory field if Category has no Subcategories (to prevent weird dropdown with nothing to select)

I have tried to investigate two possible alternatives to achieve step 3:

A) Make dynamic condition into Subcategory selection's "Only visible if..." field

B) Make a hook that fires when Category changes, then hides Subcategory field if Category has no children

So far I haven't been successful in either. Conditions I've tried always lead to hidden field, and I haven't been able to find set up a hook that fires on field change.

So here's the question (finally): Is there a way to alter field visibility in API, for example in ready.php or inside a hook? In API I could loop through categories, find the ones that have children and then make a selector based on their IDs.

[Robin S]

9 hours ago, iipa said:

Is there a way to alter field visibility in API, for example in ready.php or inside a hook?

Here's an example...

The page structure:

Some pet species have breed child pages and some do not.

The selector string for selectable pages for the breed field is "parent=page.species".

In ready.php:

$wire->addHookAfter('ProcessPageEdit::buildForm', function(HookEvent $event) {
	/* @var InputfieldForm $form */
	$form = $event->return;
	$breed_field = $form->getChildByName('breed');
	if(!$breed_field) return;
	$species_with_breeds = $event->wire('pages')->find('parent=/selects/pets/, children.count>0');
	$breed_field->showIf = 'species=' . $species_with_breeds->implode('|', 'id');
});

[iipa]

Thank you @Robin S, that is exactly what I need! Referring to a field through form in hooks is something I haven't come across yet. It's always exciting to find new things to explore!