Use the Read Permission / $_GET dont work

Hello,
i will write a extra Permission to have only access if the user is the Creator of the Collection Item or he is on the Accesslist. In my Test i use the $_GET Var to use the different Settings for the Filter. But its don’t work but if i ask for the Parameter with var_dump it’s work only the IF dont work. Have you any Ideas? or a better way to Access only Creators of the Collection Item or on the Access List for this item.

Thanks for your Help.

I don’t really use these permissions (they are confusing). I didn’t test that code, but this basic concept might work…

if ($entry['_by'] == $context->user['_id']
   || in_array($context->user['_id'], $entry['custom_account_array'])) {
    // set filter
}

I would use the collections.find.before event