Spring MVC: @SessionAttributes shared among controllers?

Question

I have an abstract controller support class for searches and result lists:

@Controller
@SessionAttributes("query")
public abstract class SearchController<Q extends SearchQuery> {
    @RequestMapping
    public String performSearch(@ModelAttribute("query") Q query) {
        ....
    }

    @ModelAttribute("query")
    public abstract Q createDefaultSearchQuery();
}

Several actual search controllers extend this base class.

After having accessed one of the controllers (say /searchBooks.html using BookSearchQuery implements SearchQuery) the query is correctly stored in the session, available for subsequent requests.

However, when I access another controller (say /searchAuthors.html using AuthorSearchQuery implements SearchQuery) the query from the last request (BookSearchQuery) is still being used for the new controller causing a ClassCastException later on.

I have tried moving the @SessionAttribute annotation from the support class to the implementation classes, to no avail.

Is there something I'm doing wrong or is this by design? What can I do?

Thanks a lot!

Answer 1

Using @SessionAttributes this objects will be stored in your HttpSession with the same name and they will be accessible (shared) from different controllers. So, Spring is acting correctly.

I think the best approach in your scenario is rename this attribute in every subclass ("BookQuery", "AutorQuery", ...). Not very elegant at all :(