抛出数据库错误异常时可以回滚事务吗？

Question

I have a large data set that needs to be written to the database when posted to the server, but it's possible that a bug in the client editor is added extra records that trigger an "integrity constraint violation".

My problem is that when I reach the point in the data where the error is trigger, then a lot of the previous data has already been updated in the database. I need to rollback and reject the posted data.

Here's my controller's action.

/**
 * Handles saving data from the network editor.
 */
public function json_save()
{
    if($this->request->is('post'))
    {
        $result = array();
        $data = $this->request->input('json_decode');
        if(isset($data->network_id) && !empty($data->network_id))
        {
            $dataSource = $this->Node->getDataSource();
            $dataSource->begin();

            $result['nodes'] = $this->updateModel($data->network_id, $this->Node, 'nodes', $data, array(
                'ParamValue'
            ));
            $result['connections'] = $this->updateModel($data->network_id, $this->Connection, 'connections', $data);

            $dataSource->commit();

            $this->viewClass = 'Json';
            $this->set('result', $result);
            $this->set('_serialize', array(
                'result'
            ));

            return;
        }
    }

    throw new ErrorException('Posted data missing.');
}

My controller's updateModel function performs a few deletes and updates to the models $this->Node and $this->Connection .

How do I roll back upon an "integrity constraint violation" which is usually thrown during updating of the $this->Connection model.

I'm not sure if it's a PHP exception that I can catch and then do a rollback, or if there is a different way to catch it.

Answer 1

You can do a :

$dataSource->begin();

try {
  // The queries here.
} catch (Exception $e) {
  $dataSource->rollback();
  throw $e;
}

$dataSource->commit();