Question

希望有人可以在这里提出建议。我对Rails相当新，并探索Rails 4.0中的变化。我在Rails 4.0中构建了这个简单的食谱书应用程序。我有食谱的主要模型（名称，cook_time，oven_temp，说明等）。因为一些食谱可能有5种成分而其他食谱可能有20种，我想在一个带有has_many关联的单独模型中打破成分。所以食谱has_many成分和accepts_nested_attributes_for：成分。以下是模型：

recipe.rb

class Recipe < ActiveRecord::Base
  belongs_to :user
  belongs_to :category
  has_many :ingredients, :dependent => :destroy

  validates :name, presence: true, length: { maximum: 50 }

  accepts_nested_attributes_for :ingredients, 
                :reject_if => lambda { |a| a[:name].blank? },
                            :allow_destroy => true
end

ingredient.rb

class Ingredient < ActiveRecord::Base
  belongs_to :recipe
end

提醒：Rails 4.0不再使用attr_accessible，而是使用强params将赋值移动到控制器中。

recipes_controller.rb

class RecipesController < ApplicationController
  before_action :find_recipe, only: [:show, :edit, :update, :destroy]
  before_action :set_current_user, except: [:index, :show]
  respond_to :html, :js

  ...

  def edit
  end

  def update
    if @recipe.update_attributes(recipe_params)
      redirect_to @recipe
    else
      render :edit
    end
  end

...

  def find_recipe
    @recipe = Recipe.find(params[:id])
  end

private

  def recipe_params
    params.require(:recipe).permit( :id, :name, :category_id, :cook_time, :oven_temp, :calories, :instructions, :notes, :email, ingredients_attributes: [:id, :name])
  end

end

我正在使用nathanvda出色的Cocoon gem动态管理嵌套表单字段，它在'recipes #new'中运行良好，并正确保存信息。但是，成分字段不会出现在“食谱#edit”视图中！这是我的'form'和ingredients_fields partials的代码。

_form.html.erb（缩写）

<%= form_for @recipe, html: { class: 'form-horizontal' } do |f| %>

  <fieldset>
  <legend>Main Information</legend>

    <div class="field form-group">
      <%= f.label :name, "Recipe name", class: "col-lg-2 control-label" %>
      <div class="col-lg-5">
        <%= f.text_field :name, class: "form-control" %>
      </div>
    </div>

    <div class="field form-group">
      <%= f.label :cook_time, class: "col-lg-2 control-label" %>
      <div class="col-lg-5">
        <%= f.text_field :cook_time, class: "form-control" %>
      </div>
    </div>
...
  </fieldset>

  <legend>Ingredients</legend>
  <p>Number of ingredients: <%= f.object.ingredients.count unless f.object.ingredients.nil? %></p>
  <fieldset id="ingredients">
    <% f.fields_for :ingredients do |builder| %>
      <%= render 'ingredient_fields', :f => builder %>
    <% end %>
    <p class="links">
      <%= link_to_add_association 'add ingredient', f, :ingredients, { class:"btn btn-primary" } %>
    </p>
  </fieldset>

  <fieldset>
  <legend>How to make it</legend>
  <div class="field form-group">
    <%= f.label :instructions, class: "col-lg-2 control-label" %>
      <div class="col-lg-5">
        <%= f.text_area :instructions, class: "form-control", rows: "7" %>
      </div>
    </div>
 ...
    </div>
  </fieldset>
<% end %>

_ingredients_fields.html.erb

<div class="nested-fields">
  <div class="form-group">
    <%= f.label :name, "Ingredient", class: "col-lg-2 control-label" %>
    <div class="col-lg-5">
      <%= f.text_field :name, class: "form-control" %>
    </div>
    <%= link_to_remove_association "remove", f %>
  </div>
</div>

正如我所说，非常简单，删除了所有错误检查和消息，只是基础知识。关于我缺少什么的任何想法？我知道当我从节目视图加载编辑时，配方中有成分。提前感谢任何建议！

凯文

Answer 1

确认。它就像'='符号一样简单 - 必须查看＆lt;％f.fields_for ...％＆gt;一千次，只是没有注意到我错过了添加＆lt;％=。

Answer 2

SELECT
    a.id
    b.id
FROM
    table1 AS a
JOIN
    table2 AS b
ON
    a.id = b.id

Rails 4.0＆amp; Cocoon：fields_for下的嵌套字段不会显示在“编辑”中

2 个答案: