Rails的“未定义方法"从布局视图调用辅助方法时 [英] rails "undefined method" when invoking a helper method from layout view

问题描述

我有一个帮助器方法可以在我的应用程序控制器中获取当前购物车:

I have an helper method in to get the current shopping cart in my application controller:

class ApplicationController < ActionController::Base
  protect_from_forgery

  helper :all # include all helpers, all the time

  private

  def current_cart
    if session[:cart_id]
      @current_cart ||= Cart.find(session[:cart_id])
      session[:cart_id] = nil if @current_cart.purchased_at
    end
    if session[:cart_id].nil?
      @current_cart = Cart.create!
      session[:cart_id] = @current_cart.id
    end
    @current_cart
  end

end

我可以从大多数视图中调用该方法，但是我想在views/layout/application.html.erb文件中使用该方法， 像这样:

I can call the method from most of my views, but I want to use it in the views/layout/application.html.erb file, like this:

<div id="cart_menu">
    <ul>
    <li>
      <%= image_tag("cart.jpg")%>
    </li>
    <li>
      <%= link_to "#{current_cart.number_of_items}", current_cart_url %>
    </li>
    <li>
          <a href="/checkout/">Checkout</a>
        </li>
    </ul>
</div>

但是当我尝试这样做时，我会得到一个

But when I try that, I get an

undefined local variable or method `current_cart' for #<#<Class:0x2d2d834>:0x2d2b908>

错误..

有什么想法吗?

推荐答案

将helper_method :current_cart添加到您的应用程序控制器中.

Add helper_method :current_cart to your application controller.

class ApplicationController < ActionController::Base
  protect_from_forgery
  helper_method :current_cart
  ...
end

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