saving related orm models with new ORM_Validation_Exception class

Model_Test.php

<?php
	public function save(Validate $validate = NULL)
	{
		DB::query(NULL, 'START TRANSACTION')->execute();

		try
		{
			parent::save($validate);
		}
		catch (ORM_Validation_Exception $e)
		// No need to handle it until the end
		// Any related model will simply merge its exception to $e
		{}

		// Let's try saving a related model if it has been altered
		if (count($this->_related['item']->_changed) > 0)
		{
			$item = $this->_related['item'];

			// Save the related item model
			try
			{
				// Add the foreign key
				$item->test_id = $this->id;

				$item->save();
			}
			catch (ORM_validation_Exception $x)
			{
				// Create an exception if one was not thrown by the parent model saving
				if ( ! isset($e))
				{
					$e = new ORM_Validation_Exception($this->_object_name, $this->validate());
				}

				// The merge method will namespace errors automatically based on the alias of the relationship
				$e->merge('item', $x);
			}
		}

		if (isset($e))
		{
			// If any of the models threw an exception, we need to rollback
			DB::query(NULL, 'ROLLBACK')->execute();
			throw $e;
		}
		else
		{
			DB::query(NULL, 'COMMIT')->execute();
		}

		// All went well
		return $this;
	}