How does a database transaction work?

dmitry_fedyuk · January 27, 2016, 6:58pm

Context: How does \Magento\Shipping\Controller\Adminhtml\Order\Shipment\Save::_saveShipment() work?

Part 1: adding objects (models) to a transaction

magento/magento2/blob/720667e/lib/internal/Magento/Framework/DB/Transaction.php#L88-L102


/**
 * Adding object for using in transaction
 *
 * @param \Magento\Framework\Model\AbstractModel $object
 * @param string $alias
 * @return $this
 */
public function addObject(\Magento\Framework\Model\AbstractModel $object, $alias = '')
{
    $this->_objects[] = $object;
    if (!empty($alias)) {
        $this->_objectsByAlias[$alias] = $object;
    }
    return $this;
}

Part 2: executing the transaction

github.com

magento/magento2/blob/720667e/lib/internal/Magento/Framework/DB/Transaction.php#L116-L122


/**
 * Initialize objects save transaction
 *
 * @return $this
 * @throws \Exception
 */
public function save()

Details: How does \Magento/Framework/DB/Transaction::_startTransaction() work?

github.com

magento/magento2/blob/720667e/lib/internal/Magento/Framework/DB/Transaction.php#L128-L130


foreach ($this->_objects as $object) {
    $object->save();
}

github.com

magento/magento2/blob/720667e/lib/internal/Magento/Framework/DB/Transaction.php#L143-L148


if ($error) {
    $this->_rollbackTransaction();
    throw $error;
} else {
    $this->_commitTransaction();
}

Details: How does \Magento/Framework/DB/Transaction::_commitTransaction() work?

dmitry_fedyuk · January 27, 2016, 7:57pm