多態關聯不保存價值

Question

我的模型：

class LineItem < ActiveRecord::Base 
    attr_accessible :itemable 
    belongs_to :itemable, polymorphic: true 

    belongs_to :lead 
    belongs_to :cart 


end 

class House < ActiveRecord::Base 
    has_many :line_items, :as => :itemable 
end 

class Appartment < ActiveRecord::Base 
    has_many :line_items, :as => :itemable 
end 

line_item_controller：

def create 
     @line_item = @cart.line_items.build item: @object 
     respond_to do |format| 
     if @line_item.save 
      format.html { redirect_to @line_item.cart, 
      notice: 'Vakantiehuis toegevoegd in lijst.' } 
      format.json { render action: 'show', 
      status: :created, location: @line_item } 
     else 
      format.html { render action: 'new' } 
      format.json { render json: @line_item.errors, 
      status: :unprocessable_entity } 
     end 
     end 
    end 

private 
    def create_object 
     id = params[:house_id] || params[:appartment_id] 

     model = "House" if params[:house_id] 
     model = "Apartment" if params[:apartment_id] 
     model = model.constantize 

     @object = model.find(id) 
    end 

當一個新的項目列表中創建在DE TABLE line_items值（itemable_id，itemable_type）不會被保存。我在這裏做錯了什麼？ thanks..remco

Answer 1

嘗試更換：

@cart.line_items.build item: @object 

到：

@cart.line_items.build itemable: @object