Nested PDO transactions

When using PDO you can't have nested transactions , so if you call multiple method that have transactions in the same one , you get an error like " a transaction already started" .

To handle this it's very simple ifyou use a database that handle SAVE POINTS , just extend PDO like this

/**
 * This class extends native PDO one but allow nested transactions
 * by using the SQL statements `SAVEPOINT', 'RELEASE SAVEPOINT' AND 'ROLLBACK SAVEPOINT'
 */
class ExtendedPdo extends PDO
{

 /**
 * @var array Database drivers that support SAVEPOINT * statements.
 */
 protected static $_supportedDrivers = array("pgsql", "mysql");

 /**
 * @var int the current transaction depth
 */
 protected $_transactionDepth = 0;


 /**
 * Test if database driver support savepoints
 *
 * @return bool
 */
 protected function hasSavepoint()
 {
 return in_array($this->getAttribute(PDO::ATTR_DRIVER_NAME),
 self::$_supportedDrivers);
 }


 /**
 * Start transaction
 *
 * @return bool|void
 */
 public function beginTransaction()
 {
 if($this->_transactionDepth == 0 || !$this->hasSavepoint()) {
 parent::beginTransaction();
 } else {
 $this->exec("SAVEPOINT LEVEL{$this->_transactionDepth}");
 }

 $this->_transactionDepth++;
 }

 /**
 * Commit current transaction
 *
 * @return bool|void
 */
 public function commit()
 {
 $this->_transactionDepth--;

 if($this->_transactionDepth == 0 || !$this->hasSavepoint()) {
 parent::commit();
 } else {
 $this->exec("RELEASE SAVEPOINT LEVEL{$this->_transactionDepth}");
 }
 }

 /**
 * Rollback current transaction,
 *
 * @throws PDOException if there is no transaction started
 * @return bool|void
 */
 public function rollBack()
 {

 if ($this->_transactionDepth == 0) {
 throw new PDOException('Rollback error : There is no transaction started');
 }

 $this->_transactionDepth--;

 if($this->_transactionDepth == 0 || !$this->hasSavepoint()) {
 parent::rollBack();
 } else {
 $this->exec("ROLLBACK TO SAVEPOINT LEVEL{$this->_transactionDepth}");
 }
 }

}

enjoy .