symfony2 routing requirements combining 2 parameters - symfony

Question

So I got this in my routing.yml:
requirements:
var1: \d+
var2: \d+
Both are checked on their own and valid.
I need to check the combination of the 2, since the combination is not always valid.
For this case I need to check the relation between 2 objects in the database, the first should be the parent of the second.
I can do this in the controller, but I don't really like that implementation. Also, I need this same check for more than 1 route.
How would I add another requirement that checks the combination? Can I define a method in the controller class that would be called?
Or would the best solution be something like:
public function indexAction($var1, $var2)
{
$result = $this->checkRelation($var1, $var2);
if ($result) {
// return errorpage
return $result;
}
// ...
}

Answer 1

So as I understand your question, you want the following:
/parent/child/ --> returns 200
/not_parent/not_child --> returns 404
The Symfony2 Routing component doesn't do this natively, but you could extend it.
http://symfony.com/doc/master/cmf/cookbook/using-a-custom-route-repository.html

Answer 2

The final solution I went with was the following:
add a method checkRelation that requires all parameters
run a query inside that method to check if everything is ok.
return false when there is a problem, return true when values are ok. (alternatively you can return an object or something)
in the action I check if the value is false, if so I return a generic "not found" page for the specific controller.
In all this is very similar to what I posted in my initial question.
When using the same checkRelation in multiple controllers it might be a good idea to move it (partially) to a repository-class or something similar to prevent duplication of code/logic.