Rails 4 - 在视图中访问连接表值 [英] Rails 4 - Access Join Table Value in views

问题描述

我有以下型号

类配方

我已经通过 rails 控制台检查过这个 has_many 通过多对多关系运作良好.

连接表 RecipeIngredient 有一个属性，在模式中是:

t.text "金额"

我想显示来自 Ingredient 的名称以及来自 RecipeIngredient 的与 Recipe 关联的数量.

我在 RecipeController 的 show action 中包含了以下几行:

def 显示@recipe = Recipe.includes(:ingredients).find(params[:id])结尾

这里是 recipes/show.html.erb:

<% title @recipe.name %><div class="col-md-12"><div class="group"><%= link_to("Edit", edit_recipe_path(@recipe), class: "btn btn-primary pull-right")%>

<h2><%=@recipe.name %></h2><p><%=@recipe.description%></p><ul>成分:<% @recipe.ingredients.each 做 |i|ri = i.recipe_ingredients.where("recipe_id: ?", @recipe.id) %><li><%=link_to(i.name,成分路径(i))%></li><p><%=ri.amount %</p><%结束%>

上面的代码在没有连接表部分的情况下运行良好.但是在引入之后，Recipes#show 中的 NoMethodError 被引发，告诉这是一个未定义的方法.

那么我如何访问该值?

解决方案

@recipe.ingredients.select('ingredients.*, recipe_ingredients.amount').each do |i|<li><%=link_to(i.name,成分路径(i))%></li><p><%=i.amount %</p>结尾

-- 可能是您可以为该特定属性金额"使用委托

I have the following models

class Recipe < ActiveRecord::Base
  has_many :recipe_ingredients
  has_many :ingredients, through: :recipe_ingredients
end

class Ingredient < ActiveRecord::Base
  has_many :recipe_ingredients
  has_many :recipes, through: :recipe_ingredients
end

class RecipeIngredient < ActiveRecord::Base
  belongs_to :recipe
  belongs_to :ingredient
end

I have checked through rails console that this has_many through many-to-many relation works well.

There is one attribute in the join table RecipeIngredient, in schema it is:

t.text "amount"

I would like to display the name from Ingredient and the amount from RecipeIngredient associated with Recipe.

I have included the following lines in RecipeController's show action:

def show
  @recipe = Recipe.includes(:ingredients).find(params[:id])
end

Here's recipes/show.html.erb:

<% title @recipe.name %>

<div class="col-md-12">

  <div class="group">
    <%= link_to("Edit", edit_recipe_path(@recipe), class: "btn btn-primary pull-right")%>
  </div>
  <h2><%= @recipe.name %></h2>
  <p><%= @recipe.description %></p>
  <ul>Ingredients:
    <% @recipe.ingredients.each do |i| ri = i.recipe_ingredients.where("recipe_id: ?", @recipe.id) %>
      <li><%= link_to(i.name, ingredient_path(i)) %></li>
      <p><%= ri.amount %></p>
    <% end %>
</div>

The above code works well without the join table part. But after it was introduced, an NoMethodError in Recipes#show is raised, telling this is an undefined method.

How can I access the value then?

解决方案

@recipe.ingredients.select('ingredients.*, recipe_ingredients.amount').each do |i|
  <li><%= link_to(i.name, ingredient_path(i)) %></li>
  <p><%= i.amount %></p>
end

-- may be u can use delegates for that particular attribute "amount"

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