WP_Model-new-filtering-system.php

<?php
Abstract Class WP_Model implements JsonSerializable{
  ...

  public function isFilterProperty($attribute){
    return (
      (
        isset($this->filter) &&
        in_array($attribute, $this->filter) &&
        method_exists($this, ('_filter'. ucfirst($attribute)))
      ) || (  
        count(array_filter(array_keys($this->filter), 'is_string')) > 0 &&
        isset($this->filter) &&
        in_array($attribute, array_keys($this->filter)) &&
        isset($this->filter[$attribute]) &&
        function_exists($this->filter[$attribute])
        
      )
    );
  }

  public function getFilterProperty($attribute){
    if( count(array_filter(array_keys($this->filter), 'is_string')) > 0 &&
        isset($this->filter[$attribute]) &&
        function_exists($this->filter[$attribute])) {

      return ($this->filter[$attribute]($this->get($attribute)));
    }

    return call_user_func_array([$this, ('_filter'. ucfirst($attribute))], [$this->get($attribute)]);
  }
}