Call an action without any interaction

Is it possible to call an controller action without interaction within a template?

I want to convert a number to an specific string like this:

switch (s){
    case 1: return "foo";
    case 2: return "bar";
    // ...
}

I want to do this in an each loop => each over items from my model, convert property s from each item to a specific string.

Well I probably could do this in an afterModel hook - but I would like to do it from the template.