how-to-set-form-id-in-rails

 form_remote_tag(:url => { :action => :create }, :update => 'main_list', :position => :bottom, :html => {:id => 'main_input' }) 

http://api.rubyonrails.org/classes/ActionView/Helpers/FormOptionsHelper.html#method-i-options_from_collection_for_select