Rails - Apr 2006 - automatic URI encoding on url_for?

I am trying to store a hash in a URL so that a search query can be
stored as a link.  Here is my code:

link_to(''blah'', url_for({:controller =>
''search'',
                           :action => ''advanced'',
                           :query => @query,
                           :page => n})

@query is the hash I''m trying to store and later retrieve.  Right now
it appears to be turning into a plain string with all the keys and
values concatenated together.  I want to make it so that query is
automatically freeze-dried into URI-safe stuff and then reconstituted
as an instance variable when the URI is requested again.  Any
suggestions?

Thanks,
Carl