Get current action path / url including query string? (Rails)

A simple question: how do I get the path or full URL of the current action, INCLUDING the query string?

I want to save it in a session variable as follows:

def show
  @thingy = Thingy.find(params[:id])

  session[:some_var] = current_url

  ...
end

Right now I'm doing the following, but it seems a bit heavy (especially for specifying the query string parameters separately):

def show
  @thingy = Thingy.find(params[:id])

  session[:some_var] = thingy_path(@thingy, :q1 => params[:q1], :q2 => params[:q2])

  ...
end