Extending Database Drivers

Category:Databases Category:Database Drivers

Much complaints about not being able to extend the CI database class. In the docs it says this can't be done, but here is a simple solution that fits it all! [b]Don't believe it?, well read on..[/b]

[size=4][b]The solution comes in 3 simple steps:[/b][/size]

1. If you haven't already extended your loader class, you do so by creating the file MY_Loader.php into your libraries directory in the application path. It's content is at first:

[code] <?php

class MY_Loader extends CI_Loader {

}

?> [/code]

2. Then you add the following function to your MY_Loader class:

[code] /** * Database Loader * * @access public * @param string the DB credentials * @param bool whether to return the DB object * @param bool whether to enable active record (this allows us to override the config setting) * @return object */ function database($params = '', $return = FALSE, $active_record = FALSE) { // Do we even need to load the database class? if (class_exists('CI_DB') AND $return == FALSE AND $active_record == FALSE) { return FALSE; }

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

        // Load the DB class
        $db =& DB($params, $active_record);

        $my_driver = config_item('subclass_prefix').'DB_'.$db->dbdriver.'_driver';
        $my_driver_file = APPPATH.'libraries/'.$my_driver.EXT;

        if (file_exists($my_driver_file))
        {
            require_once($my_driver_file);
            $db =& new $my_driver(get_object_vars($db));
        }

        if ($return === TRUE)
        {
            return $db;
        }
        // Grab the super object
        $CI =& get_instance();

        // Initialize the db variable.  Needed to prevent
        // reference errors with some configurations
        $CI->db = '';
        $CI->db = $db;
        // Assign the DB object to any existing models
        $this->_ci_assign_to_models();
}

[/code]

3. Now you are ready to create your Database driver extension class, that you name depending on which driver (mysql, postgre, ..) you use. You put it also in your applications libraries directory, name it accordingly MY_DB_mysql_driver.php (again substitute the mysql part for whatever is accurate):

[code] <?php

class MY_DB_mysql_driver extends CI_DB_mysql_driver {

function __construct($params){ parent::__construct($params); log_message('debug', 'Extended DB driver class instantiated!'); }

function idonothing(){ return $this; }

} ?> [/code]

There you are done! Congrats, now you can use the following, where idonothing() is the sample function from above, that just does nothing else than pass on your db object.

[code] $this->db->from('sometable')->idonothing()->limit(1)->get(); [/code]