Another question from me, a new person to ROR. table a (has column id and name) and table b (has column id and name), they have many_many relationship. so, joint table a_b introduced. a_b only has a_id and b_id. I am using <% for b in @bs %> <%= check_box("b", b.id, (@a.bs.include?(b) ? {:checked => ''checked''} : {:checked => false} )) %> <%= b.name %> <% end %> to show all available b for a. it works. I am using def update @a = A.find(params[:id]) b = B.find(params["b"].to_i) unless @a.bs.include?(b) @a.bs << b end if @a.update_attributes(params[:a]) flash[:notice] = ''A was successfully updated.'' redirect_to :action => ''show'', :id => @a else render :action => ''edit'' end end to save all info into table a and joint table a_b however, I got the following error message: NoMethodError in AController#update undefined method `to_i'' for {"1"=>"1", "2"=>"0", "3"=>"0", "4"=>"1"}:HashWithIndifferentAccess Any idea how to fix it? thanks. -- Posted via http://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---