ruby on rails - Passing parameters into model -

rails 3.0.3 ruby 1.9.2p0

the problem:

i have users table has many items, item(s) in turn therefore belongs users.

in model item.rb attempt save item along value user.id have:

self.user_id = @user.id 

this give me error

called id nil, mistakenly 4 -- if wanted id of nil, use object_id 

this causing confusion can't find in show.html.erb 'wraps' page <%= @user.id %> displays correct id on page

many in advance

** edit ** shorten action action upon want parameter passed

class itemscontroller < applicationcontroller    def redirect     @item = item.find_by_shortened(params[:shortened])     if @item       #redirect_to @item.original       redirect_to @item.original     else       redirect_to :shorten     end   end    def shorten     @host = request.host_with_port     @user = current_user 

you need load @user model in every action require access it. having render in show action not guarantee loaded in update action.

usually need have in controller:

class userscontroller < applicationcontroller   before_filter :load_user, :except => [ :index, :new, :create ]    # ...  protected   def load_user     @user = user.find(params[:user_id] || params[:id])   rescue activerecord::recordnotfound     render(:text => 'record not found')   end end