form_for redirect to another controller

I have 2 controllers foo, bar and I'm using searchlogic gem to search
products inside both controllers. All works great but I want to
implement now custom form_for from foo view to search products for bar
controllers, how to do this ?

I try something like this:

<% form_for @search, :url => {:controller => "bar", :action => "index"}
do |f| %>

but its not work :/, pls help

The same problem i also have