Error "Notice: Undefined offset: 1" when I activate plugin

August 7, 2023

I try to write simple plugin om WordPress. But when I try activate it, I get errow "Notice: Undefined offset: 1" How I fix it? Thank you for your attention.

if (!defined('ABSPATH')) {
   die;
}

class ledproperty {

   public function register() {
      add_action('init', [$this, 'custom_post_type']);
   }

   public function custom_post_type() {
      register_post_type('property', 
      array(
         'public' => true,
         'has_archive' => true,
         'rewrite' => array('slug' => 'properties'),
         'label' => 'Property',
         'supports' => array('title', 'editor', 'thumbnail')
      
      ));
   }

   static function activation() {
      flush_rewrite_rules();
   }
   static function deactivation() {
      flush_rewrite_rules();
   }
}
if(class_exists('ledproperty')) {
   $ledproperty = new ledproperty();
   $ledproperty -> register();
}

register_activation_hook(__FILE__, array($ledproperty), 'activation');
register_deactivation_hook(__FILE__, array($ledproperty), 'deactivation');

>Solution :

It looks like you have a couple of issues in your code that are causing the "Notice: Undefined offset: 1" error. Let’s address those issues and correct the code:

Issue with the register_activation_hook() and register_deactivation_hook():
You’re passing the parameters incorrectly for the register_activation_hook() and register_deactivation_hook() functions. You need to provide the hook functions as callbacks in an array. Also, you should call these functions inside the ledproperty class.

Issue with the order of function calls:
You’re trying to use the $ledproperty object before it’s defined. You need to define the object before using it in the activation and deactivation hooks.

Here’s the corrected version of your code:

if (!defined('ABSPATH')) {
   die;
}

class ledproperty {

   public function __construct() {
      $this->register();
   }

   public function register() {
      add_action('init', [$this, 'custom_post_type']);
      register_activation_hook(__FILE__, [$this, 'activation']);
      register_deactivation_hook(__FILE__, [$this, 'deactivation']);
   }

   public function custom_post_type() {
      register_post_type('property', 
      array(
         'public' => true,
         'has_archive' => true,
         'rewrite' => array('slug' => 'properties'),
         'label' => 'Property',
         'supports' => array('title', 'editor', 'thumbnail')
      
      ));
   }

   public function activation() {
      flush_rewrite_rules();
   }

   public function deactivation() {
      flush_rewrite_rules();
   }
}

if(class_exists('ledproperty')) {
   $ledproperty = new ledproperty();
}

In this corrected code:

I moved the register_activation_hook() and register_deactivation_hook() calls inside the register() method of the ledproperty class.

The __construct() method is used to call the register() method when an object of the ledproperty class is created.

The $ledproperty object is now created after the class definition.
With these changes, your plugin should now activate without any "Undefined offset" error