一个简单的使用group_by的rails 3.1视图 [英] a simple rails 3.1 view using group_by

问题描述

我在我正在制作的网站上有一个菜单，它是food_items的菜单。表中的每个记录还包含一个类别字段。这个类别可以是汉堡包，零食，饮料或其他任何他们想要将食物分类的东西。

我试图显示菜单，按这个分类分组领域。我到目前为止的尝试：

  food_item_menus_controller.rb 
 ... 
 def food_list 
 @食物= FoodItem.all 
 @food_list = @ foods.group_by {| t | t.category} 
结束
 
 
 views / food_item_menus / index.html.haml 
 = @ food_list.group_by（@ food_items.category）.each do | food_list | 
％p 
 = food_list.name 
％ul 
  -  for food_items in food_items 
％li 
 = food_items.name 
  

我的错误是我有一个零对象。我想我的电话@foods没有返回任何东西。

  models / food_item.rb 
 class FoodItem< ActiveRecord :: Base 
 has_many：menus，：through => ：food_item_menus 
 has_many：food_item_menus 
 end 
  

我是否设置了错误的内容？或者，我的想法是错误的，如果我在视图中调用@foods，它实际上并没有调用我在控制器中设置的变量？我越想弄清楚这一点，我越是对一切事情感到困惑，包括基础知识。

您的观点代码充满了错误，它应该是这样的：

  = @ food_list.each do | category，food_items | 
％p 
 =类别
％ul 
  -  food_items.each do | food | 
％li 
 = food.name 
  

错误细分：

• @ food_list.group_by（@ food_items.category）.each do | food_list |
- 您还没有为任何地方的 @food_items 赋值; @food_list 被赋值为控制器中 group_by 调用的结果，所以在这里你调用它两次; group_by 会返回一个散列，因此您的每个块应该有两个参数，而不是一个。


• for food_items in food_items - 为迭代变量和迭代器使用相同的变量名称; food_items 没有在任何地方分配一个值。

I have a menu on a site I am working on, menu of food_items. Each of the records in the table also contains a field of category. This category can be burgers, munchies, drinks, or anything else they want to categorize food items by.

I am trying to display the menu, with items grouped by this category field. My attempt so far:

food_item_menus_controller.rb
...
def food_list
  @foods = FoodItem.all
  @food_list = @foods.group_by { |t| t.category }
end


views/food_item_menus/index.html.haml
= @food_list.group_by (@food_items.category).each do |food_list|
  %p
    = food_list.name
  %ul
    -  for food_items in food_items
      %li
        = food_items.name

My error is that I have a nil object. I guess my call to @foods isn't returning anything.

models/food_item.rb
class FoodItem < ActiveRecord::Base
  has_many :menus, :through => :food_item_menus
  has_many :food_item_menus
end

Did I set up something wrong? Or is my thinking wrong that if I call @foods in the view, it's not actually calling the variable I set in the controller? The more I try to figure this out, the more I am just getting confused about everything, including the basics.

解决方案

Your view code is full of errors, it should be something like this:

= @food_list.each do |category, food_items|
  %p
    = category
  %ul
    - food_items.each do |food|
      %li
        = food.name

Breakdown of errors:

• @food_list.group_by(@food_items.category).each do |food_list| - you haven't assigned a value to @food_items anywhere; @food_list is assigned as the result from a group_by call in your controller, so here you're calling it twice; group_by returns a hash, so your each block should have two arguments, not one.
• for food_items in food_items - using the same variable name for the iterated variable and the iterator; food_items is not assigned a value anywhere.

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