ruby on rails - How to pass variables to render_to_string?

Question

Trying to do the following

@message = render_to_string ( :sender => sender, :template => "template" )          

But when accessing @sender in template it turns out to be nil:NilClass. Double checked if I pass the right variable and it's totally fine. Maybe there are other way to pass variables to render_to_string?

question from:https://stackoverflow.com/questions/3714198/how-to-pass-variables-to-render-to-string