Question

尝试将简单的库存控制系统添加到我的rails应用程序中在现有产品数据库中添加了库存字段

创建了一个名为print_stock的辅助方法，并将其添加到Products#index文件中但是当我运行应用程序时

NoMethodError in Products#index, undefined method `print_stock' for #<#Class:0x007f821b670530>:0x007f821e170898>

向产品添加库存

class AddStockToProducts < ActiveRecord::Migration
  def change
    add_column :products, :stock, :integer, default: 0
  end
end

的index.html

<tbody>
    <% @products.each do |product| %>
      <tr>
        <td><%= image_tag "products/#{product.image_url}" %></td>
        <td><%= product.title %></td>
        <td><%= print_price(product.price) %></td>
        **<td><%= print_stock(product.stock) %></td>**<---error
        <td><%= product.description %></td>
        <td><%= link_to 'Show', product_path(product) %></td>
        <td><%= link_to 'Edit', edit_product_path(product) %></td>
        <td><%= link_to 'Destroy', product, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

print.stock.rb

def print_stock(stock)
  if stock > 0
    <span class="in_stock">In Stock (XX)</span>
  else
    <span class="out_stock">Out of Stock</span>
  end
end

更新了applicationhelper

module ApplicationHelper
def print_stock(stock)
    if stock > 0
      "<span class="in_stock">In Stock (XX)</span>"
    else
      "<span class="out_stock">Out of Stock</span>"
    end
  end
end

/Users/neilpatel/Desktop/Rails/merchant/app/helpers/application_helper.rb:4: syntax error, unexpected tIDENTIFIER, expecting keyword_end "<span class="in_stock">In Stock (XX)</span>" ^ /Users/neilpatel/Desktop/Rails/merchant/app/helpers/application_helper.rb:6: syntax error, unexpected tIDENTIFIER, expecting keyword_end "<span class="out_stock">Out of Stock</span>" ^

更新了products_helper

module ProductsHelper

    def print_price(price)
        format("£%.2f",price)
    end

  def print_stock(stock)
    if stock.to_i > 0
      return true
    else
      return false
    end
  end

end

Answer 1

帮助文件名应为：

products_helper.rb

，内容应为：

module ProductsHelper
  def print_stock(stock)
    if stock.to_i > 0
      return true
    else
      return false
    end
  end
end

然后在视图中：

index.html
<table>
  <tbody>
    <% @products.each do |product| %>
      <tr>
        <td><%= image_tag "products/#{product.image_url}" %></td>
        <td><%= product.title %></td>
        <td><%= print_price(product.price) %></td>


        <td>
           <% if print_stock(product.stock) %>
              <span class="in_stock">In Stock (XX)</span>
           <% else %>
              <span class="out_stock">Out of Stock</span>
           <% end %>
        </td>

        <td><%= product.description %></td>
        <td><%= link_to 'Show', product_path(product) %></td>
        <td><%= link_to 'Edit', edit_product_path(product) %></td>
        <td><%= link_to 'Destroy', product, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

希望有所帮助：）

Answer 2

将这些行放在 application_helper.rb

中

module ApplicationHelper
  def print_stock(stock)
    if stock > 0
      "<span class="in_stock">In Stock (XX)</span>"
    else
      "<span class="out_stock">Out of Stock</span>"
    end
  end
end

Answer 3

相同的答案，但需要更改一些语法

module ApplicationHelper
 def print_stock(stock)
  if stock > 0
   "<span class='in_stock'>In Stock (XX)</span>"
  else
   "<span class='out_stock'>Out of Stock</span>"
 end
end

端

需要更改为single quotes

产品中的Rails 4 NoMethodError #index使用helper_method

3 个答案: