Ruby on rails 注册时为模型分配新用户时id=0错误

我试图允许当前用户邀请另一个用户，并将新的被邀请者分配到列表中，但当被邀请的用户去注册时，我收到了一个错误

有两个模型，用户和列表，它们与每个模型上的has_和属于多个相关。还有一个邀请模型，它包含一个令牌和被邀请者需要分配到的列表

我正在覆盖设备注册控制器：

  def new
    resource = build_resource({:invitation_token => params[:invitation_token]})
    resource.email = resource.invitation.recipient_email if resource.invitation
    resource.listings << resource.invitation.listing if resource.invitation
    respond_with resource
  end

  # POST /resource
  def create
    build_resource

    if resource.save
      if resource.active_for_authentication?
        set_flash_message :notice, :signed_up if is_navigational_format?
        sign_in(resource_name, resource)
        respond_with resource, :location => after_sign_up_path_for(resource)
      else
        set_flash_message :notice, :"signed_up_but_#{resource.inactive_message}" if is_navigational_format?
        expire_session_data_after_sign_in!
        respond_with resource, :location => after_inactive_sign_up_path_for(resource)
      end
    else
      clean_up_passwords resource
      respond_with resource
    end
  end

当我邀请一个新用户并转到“注册/新建”页面，填写表单，然后单击“提交”时，我收到以下错误：

Couldn't find Listing with id=0

以及服务器日志的以下输出：

Started POST "/users" for 127.0.0.1 at 2012-04-26 14:02:51 -0400
  Processing by RegistrationsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"KdWS08JnnbN61JwKkUsIBNDFvJZnX6E8iN3QOS9149U=", "user"=>{"invitation_token"=>"80c98940448829e7edc623f9886e6930434e245c", "listing_ids"=>"[1]", "first_name"=>"John", "last_name"=>"Williams", "email"=>"johnpkelleher@gmail.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign up"}
  Invitation Load (0.8ms)  SELECT "invitations".* FROM "invitations" WHERE "invitations"."token" = '80c98940448829e7edc623f9886e6930434e245c' LIMIT 1
  Listing Load (0.3ms)  SELECT "listings".* FROM "listings" WHERE "listings"."id" = $1 LIMIT 1  [["id", 0]]
Completed 404 Not Found in 170ms

ActiveRecord::RecordNotFound (Couldn't find Listing with id=0):
  app/controllers/registrations_controller.rb:12:in `create'

当分配的列表id为1时，为什么会出现此错误

Started POST "/users" for 127.0.0.1 at 2012-04-26 14:02:51 -0400
  Processing by RegistrationsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"KdWS08JnnbN61JwKkUsIBNDFvJZnX6E8iN3QOS9149U=", "user"=>{"invitation_token"=>"80c98940448829e7edc623f9886e6930434e245c", "listing_ids"=>"[1]", "first_name"=>"John", "last_name"=>"Williams", "email"=>"johnpkelleher@gmail.com", "password"=>"[FILTERED]", "password_confirmation"=>"[FILTERED]"}, "commit"=>"Sign up"}
  Invitation Load (0.8ms)  SELECT "invitations".* FROM "invitations" WHERE "invitations"."token" = '80c98940448829e7edc623f9886e6930434e245c' LIMIT 1
  Listing Load (0.3ms)  SELECT "listings".* FROM "listings" WHERE "listings"."id" = $1 LIMIT 1  [["id", 0]]
Completed 404 Not Found in 170ms

ActiveRecord::RecordNotFound (Couldn't find Listing with id=0):
  app/controllers/registrations_controller.rb:12:in `create'