Hi, I currently have a Rails Apps that lets users drag and drop certain elements of the webpage and updates the application based on the users choice. This is done with the help of the Rails helpers and AJAX. However I keep running into a "NoMethodError" in Ruby. NoMethodError in ProjectsController#member_change undefined method `symbolize_keys' for nil:NilClass Here is the method that is being called. My trace says that error is occurring in this line: before = u.functions_for(r.authorizable_id) u.roles << r unless u.roles.include? r u.save flag_changed = true after = u.functions_for(r.authorizable_id) And here is the function being called def member_change flag_changed = false params['u'] =~ /role_(\d+)_user_(\d+)/ drag_role_id = $1 user_id = $2 params['r'] =~ /role_(\d+)/ drop_role_id = $1 if u=User.find(user_id) if r=Role.find(drop_role_id) if drag_role_id.to_i !=0 and old_r=Role.find(drag_role_id) if drag_role_id == drop_role_id #fom A to A => nothing happen flash.now[:warning] = _('No Operation...') elsif r.authorizable_id == old_r.authorizable_id #the same project? old_r.users.delete(u) unless old_r.valid? flash.now[:warning] = _('Group "Admin" CAN NOT be EMPTY.') old_r.users << u #TODO: better recovery member_edit #if flag_changed render :action => :member_edit, :layout => 'module_with_flash' return end old_r.save r.users << u unless r.users.include? u r.save flag_changed = true before = u.functions_for(r.authorizable_id) after = u.functions_for(r.authorizable_id) added = after - before removed = before - after added.each do |f| ApplicationController::send_msg(:function,:create, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end removed.each do |f| ApplicationController::send_msg(:function,:delete, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end flash.now[:notice] = _( 'Move User to Group' ) + " #{ r.name }" else flash.now[:warning] = _('You can\'t move User between Groups that belong to different Projects.') end else before = u.functions_for(r.authorizable_id) u.roles << r unless u.roles.include? r u.save flag_changed = true after = u.functions_for(r.authorizable_id) added = after - before added.each do |f| ApplicationController::send_msg(:function,:create, {:function_name => f.name, :user_id => u.id, :project_id => r.authorizable_id }) end flash.now[:notice] = _( 'Add User into Group' ) + " #{ r.name }" end else flash.now[:warn] = _( 'Group doesn\'t exist!' ) + ": #{ r.name }" end else flash.now[:warning] = _( 'User doesn\'t exist!' ) + ": #{ u.login }" end member_edit #if flag_changed render :action => :member_edit, :layout => 'module_with_flash' end and the JavaScript used to call the function jQuery('#RemoveThisMember').droppable({accept:'.RolesUsersSelection', drop:function(ev,ui){ if (confirm("This will remove User from this Group, are you sure?")) {jQuery.ajax({data:'u=' + encodeURIComponent(jQuery(ui.draggable).attr('id')), success:function(request){jQuery('#module_content').html(request);}, type:'post', url:'/of/projects/11/member_delete'});} }, hoverClass:'ProjectRoleDropDelete_active'}) Any ideas? Thanks,