【CodeIgniter3】クエリービルダー（旧アクティブレコード）を拡張する方法

MY_Loader.php

<?php

defined('BASEPATH') OR exit('No direct script access allowed');

class MY_Loader extends CI_Loader
{

	/**
	 * Database Loader
	 *
	 * @param	mixed	$params		Database configuration options
	 * @param	bool	$return 	Whether to return the database object
	 * @param	bool	$query_builder	Whether to enable Query Builder
	 * 					(overrides the configuration setting)
	 *
	 * @return	object|bool	Database object if $return is set to TRUE,
	 * 					FALSE on failure, CI_Loader instance in any other case
	 */
	public function database($params = '', $return = FALSE, $query_builder = NULL)
	{
		// Grab the super object
		$CI = & get_instance();

		// Do we even need to load the database class?
		if ($return === FALSE && $query_builder === NULL && isset($CI->db) && is_object($CI->db) && !empty($CI->db->conn_id))
		{
			return FALSE;
		}

		require_once(BASEPATH . 'database/DB.php');

		require_once(BASEPATH . 'database/DB_driver.php');

		// ここから拡張クエリビルダークラスを読み込む処理を追加
		if (!isset($query_builder) OR $query_builder === TRUE)
		{
			require_once(BASEPATH . 'database/DB_query_builder.php');

			if (!class_exists('CI_DB', FALSE))
			{
				// 拡張したクエリビルダークラスを読み込む
				$query_builder_path = APPPATH . 'libraries/database/MY_DB_query_builder.php';
				if (file_exists($query_builder_path))
				{
					require_once($query_builder_path);
				}
			}
		}

		if ($return === TRUE)
		{
			return DB($params, $query_builder);
		}

		// Initialize the db variable. Needed to prevent
		// reference errors with some configurations
		$CI->db = '';

		// Load the DB class
		$CI->db = & DB($params, $query_builder);

		return $this;
	}

}