<?php

/**
 * Testimonial model
 *
 * @package     Nails
 * @subpackage  module-testimonial
 * @category    Model
 * @author      Nails Dev Team
 * @link
 */

namespace Nails\Testimonial\Model;

use Nails\Common\Model\Base;

class Testimonial extends Base
{
    const TABLE               = NAILS_DB_PREFIX . 'testimonial';
    const DEFAULT_SORT_COLUMN = 'quote';

    // --------------------------------------------------------------------------

    /**
     * Model constructor
     **/
    public function __construct()
    {
        parent::__construct();
        $this->searchableFields  = ['quote', 'quote_by'];
    }
}

<?php

/**
 * Testimonial model
 *
 * @package     Nails
 * @subpackage  module-testimonial
 * @category    Model
 * @author      Nails Dev Team
 * @link
 */

namespace Nails\Testimonial\Model;

use Nails\Common\Model\Base;

class Testimonial extends Base
{
    /**
     * Model constructor
     **/
    public function __construct()
    {
        parent::__construct();
        $this->table             = NAILS_DB_PREFIX . 'testimonial';
        $this->defaultSortColumn = 'quote';
        $this->searchableFields  = ['quote', 'quote_by'];
    }
}

--- 
+++ 
@@ -16,14 +16,17 @@
 
 class Testimonial extends Base
 {
+    const TABLE               = NAILS_DB_PREFIX . 'testimonial';
+    const DEFAULT_SORT_COLUMN = 'quote';
+
+    // --------------------------------------------------------------------------
+
     /**
      * Model constructor
      **/
     public function __construct()
     {
         parent::__construct();
-        $this->table             = NAILS_DB_PREFIX . 'testimonial';
-        $this->defaultSortColumn = 'quote';
         $this->searchableFields  = ['quote', 'quote_by'];
     }
 }
Use constants for model configuration
