Question

我目前正在关注敏捷Web开发手册（Rails 3）并且遇到了私有方法错误。经过数小时的研究，我找不到解决方案。

以下是我正在使用的代码，并发现了提供问题的字符串：

<td class="item_price"><%= number_to_currency(item.total_price) %></td>

有一个类似的问题/解决方案已经发布，其中解决方案是将Item类放在私有上面，但是，行项类不是私有的。

任何帮助都将不胜感激。

CODE

<% if notice %>
<p id="notice"><%= notice %></p>
<% end %>

<!-- START_HIGHLIGHT -->
<h2>Your Cart</h2>
<table>
<!-- END_HIGHLIGHT -->
  <% @cart.line_items.each do |item| %>
<!-- START_HIGHLIGHT -->
    <tr>
      <td><%= item.quantity %>&times;</td>
      <td><%= item.product.title %></td>
      <td class="item_price"><%= number_to_currency(item.total_price) %></td>
    </tr>
<!-- END_HIGHLIGHT -->
  <% end %>
 <!-- START_HIGHLIGHT -->
  <tr class="total_line">
    <td colspan="2">Total</td>
    <td class="total_cell"><%= number_to_currency(@cart.total_price) %></td>
  </tr>
<!-- END_HIGHLIGHT -->
<!-- START_HIGHLIGHT -->
</table>
<!-- END_HIGHLIGHT -->

<%= button_to 'Empty cart', @cart, method: :delete,
     data: { confirm: 'Are you sure?' } %>

错误

private method `total_price' called for #<LineItem

line_item模型

class LineItem < ActiveRecord::Base
  belongs_to :product
  belongs_to :cart
  attr_accessible :cart_id, :product_id
end

def total_price
    product.price * quantity
end

购物车型号

class Cart < ActiveRecord::Base
  has_many :line_items, dependent: :destroy

  def add_product(product_id)
    current_item = line_items.find_by_product_id(product_id)
    if current_item
      current_item.quantity += 1
    else
      current_item = line_items.build(product_id: product_id)
    end
     current_item
  end

  def total_price
     line_items.to_a.sum { |item| item.total_price }
   end
end

订单项控制器

class LineItemsController < ApplicationController
  # GET /line_items
  # GET /line_items.json
   def index
     @line_items = LineItem.all

     respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @line_items }
    end
  end

  # GET /line_items/1
  # GET /line_items/1.json
  def show
    @line_item = LineItem.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @line_item }
    end
  end

   # GET /line_items/new
   # GET /line_items/new.json
  def new
     @line_item = LineItem.new

    respond_to do |format|
       format.html # new.html.erb
       format.json { render json: @line_item }
     end
   end

   # GET /line_items/1/edit
   def edit
     @line_item = LineItem.find(params[:id])
   end

  # POST /line_items
  # POST /line_items.json
   def create
    @cart = current_cart
    product = Product.find(params[:product_id])
    @line_item = @cart.add_product(product.id)
    @line_item.product = product

    respond_to do |format|
      if @line_item.save
        format.html { redirect_to @line_item.cart,
           notice: 'Line item was successfully created.' }
        format.json { render json: @line_item,
          status: :created, location: @line_item }
      else
         format.html { render action: "new" }
         format.json { render json: @line_item.errors,
         status: :unprocessable_entity }
      end
    end
  end

   # PUT /line_items/1
   # PUT /line_items/1.json
   def update
    @line_item = LineItem.find(params[:id])

    respond_to do |format|
      if @line_item.update_attributes(params[:line_item])
        format.html { redirect_to @line_item, notice: 'Line item was successfully updated.' }
        format.json { head :no_content }
      else
         format.html { render action: "edit" }
         format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
     end
   end

  # DELETE /line_items/1
  # DELETE /line_items/1.json
  def destroy
    @line_item = LineItem.find(params[:id])
    @line_item.destroy

    respond_to do |format|
      format.html { redirect_to line_items_url }
      format.json { head :no_content }
    end
   end
end

Answer 1

您说@cart.total_price正在提供错误，但您的错误表明它正在LineItem模型中查找此功能。这可能意味着您必须在total_price模型中使用LineItem方法。你有吗？是的，正如其他人所说，最好在你的帖子中添加控制器和型号代码。

修改的

根据您在帖子中的更新，是total_price方法应该在您的课程内。这会解决问题吗？

Answer 2

在LineItem模型中total_price定义在LineItem类之外。所以它应该是：

class LineItem < ActiveRecord::Base
  belongs_to :product
  belongs_to :cart
  attr_accessible :cart_id, :product_id

  def total_price
    product.price * quantity
  end
end

ROR - 购物车中的NoMethodError＃show - 私有方法错误

2 个答案: