[Laravel] Nested transactions wrapper class

nestedtransactor.php

<?php

/**
 * Class for Laravel 3.x that provides ability to use nested transactions via SAVEPOINTs
 * (inspired from http://www.kennynet.co.uk/2008/12/02/php-pdo-nested-transactions/).
 * For now, only the default connection is supported.
 *
 * Useful in testing, when you want to start a transaction before running a test
 * and revert all its changes after it finished.
 *
 * To use this, you need to replace value under "DB" key in `application.aliases` config
 * with this class name. After this, you can continue to use Laravel-style transactions
 * (`DB::transaction`), but you need to replace all "raw PDO" transaction calls
 * (such as `DB::connection()->pdo->beginTransaction()`) with alternatives provided
 * by this class.
 */

class NestedTransactor extends \Laravel\Database {

    protected static $supported_drivers = ['pgsql', 'mysql', 'mysqli', 'sqlite'];
    protected static $transaction_level = 0;

    protected static function get_pdo() {
        return static::connection()->pdo;
    }

    protected static function nestable() {
        $current_driver = static::get_pdo()->getAttribute(\PDO::ATTR_DRIVER_NAME);
        return in_array($current_driver, static::$supported_drivers);
    }

    protected static function process_pdo($pdo_method, $sql) {
        $pdo = static::get_pdo();
        if (static::$transaction_level == 0 || !static::nestable()) {
            $pdo->{$pdo_method}();
        } else {
            $pdo->exec($sql);
        }
    }

    public static function begin_transaction() {
        static::process_pdo('beginTransaction', 'SAVEPOINT LEVEL'.static::$transaction_level);
        static::$transaction_level++;
    }

    public static function commit_transaction() {
        static::$transaction_level--;
        static::process_pdo('commit', 'RELEASE SAVEPOINT LEVEL'.static::$transaction_level);
    }

    public static function rollback_transaction() {
        static::$transaction_level--;
        static::process_pdo('rollBack', 'ROLLBACK TO SAVEPOINT LEVEL'.static::$transaction_level);
    }

    /**
     * Redefined transaction method of Laravel\Database\Connection
     * @param  callback  $callback
     * @return void
     */
    public static function transaction($callback) {
        static::begin_transaction();
        try {
            call_user_func($callback);
        } catch (\Exception $e) {
            static::rollback_transaction();
            throw $e;
        }
        return static::commit_transaction();
    }

}

Really useful. Thanks.

To everybody that will use this class not under global namespace:
Check if you prepend \ before class used in all these methods(or other way ensure that you're using right classes). Trying to retrieve PDO::ATTR_DRIVER_NAME without global namespace prefix will trigger error and I caught that quickly. But I missed Exception in catch in transaction method and it was really unpleasent bug, which caused some unrelated with database functions of laravel to not work as it supposed to. I spent half an hour to finally found the real cause. So watch out :)

Thanks for the note, @jan-j. Just have added global namespace prefix.