Lock field when populated?

[cryostar]

Is it possible to lock a field on the Edit page once it's been populated? If not, how do I prevent users from editing a field further?

[BillH]

You could use a hook as in this discussion:

Putting the hook in ready.php may well be a good plan.

[cryostar]

Thanks @BillH! Using hooks is actually on top of my head though I was just wondering if there are other straightforward solutions that don't require code.

If anyone has a requirement like I do that should make certain fields read-only when they are populated, here's how I did it (saved under ready.php):

$wire->addHookBefore('Page::loaded', function(HookEvent $event){
    $_page = $event->object;
    if($this->page->process !== 'ProcessPageEdit') return; //Run only if you're on the admin page editor
    if('specifictemplate' != $_page->template) return; //If only you want to lock it for certain fields
    if(!$_page->thatfield) return; //This is a Page Reference that returns false if there is no value

    $thatfield = $_page->getField('thatfield');
    $thatfield->collapsed = Inputfield::collapsedNoLocked;
});