Rails 多个嵌套表单

Question

这是我的第一个 Rails 项目，我正在尝试创建一个表单来添加可以具有多个属性名称和值对的产品。我遵循了几个教程，并在此处查看了几个有关嵌套表单的答案，但我对信息是否实际保存和显示信息感到困惑。我使用 Cocoon gem 动态创建额外的属性名称和值对。我尝试使用简单的嵌套形式来确保我正确地构建了模型——这就是下面的代码。我在下面包含了我项目中的相关代码。任何帮助是极大的赞赏！

controllers/products_controller.erb

class ProductsController < ApplicationController
  def index
    @products = Product.all
    gon.products = Product.all
  end

  def show
    @product = Product.find(params[:id])
    @properties = Product.find(params[:id])
  end

  def new
    @product = Product.new
    @properties = @product.properties.build
    @product_properties = @properties.product_properties.build
  end

  def create
    @product = Product.new(product_params)

    if @product.save
    redirect_to products_path,
    notice: 'The product was successfully created.'
    else
      render 'new'
    end
  end

  private
  def product_params
    params.require(:product).permit(:name, :upc, :available_on,
      :properties_attributes => [:property_name,
        :product_properties_attributes => [:value]
        ])
  end
  def get_property
    @property = Property.find(params[:property_id])
  end
end

models/product.rb

class Product < ApplicationRecord
  has_many :properties
  has_many :product_properties,
           :through => :properties
  accepts_nested_attributes_for :properties
  accepts_nested_attributes_for :product_properties
  attr_accessor :properties_attributes,
                :product_properties_attributes

  validates :name, :upc, :available_on, presence: true
  validates :name, :upc, uniqueness: true
  validates :upc, numericality: { only_integer: true }

  validates :name, length: { maximum: 1024,
    too_long: "%{count} characters is the maximum allowed" }


  validate :check_length

  def check_length
    unless upc.size == 10 or upc.size == 12 or upc.size == 13
      errors.add(:upc, "length must be 10, 12, or 13 characters")
    end
  end

  validate :expiration_date_cannot_be_in_the_past

  def expiration_date_cannot_be_in_the_past
    errors.add(:available_on, "must be a future date") if
      !available_on.blank? and available_on < Date.today
  end

end

models/property.rb

class Property < ApplicationRecord
  belongs_to :product
  has_many :product_properties
  accepts_nested_attributes_for :product_properties
  attr_accessor :property_name,
                :value,
                 :product_properties_attributes


  validates :property_name, presence: true
  validates :property_name, uniqueness: true
  validates :property_name, length: { maximum: 255,
    too_long: "%{count} characters is the maximum allowed" }
end

models/product_property.rb

class ProductProperty < ApplicationRecord
  belongs_to :property
  belongs_to :product
  attr_accessor :value

  validates :value, presence: true
  validates :value, length: { maximum: 255,
    too_long: "%{count} characters is the maximum allowed" }

end

views/products/new.html.erb

<h1>New Product</h1>
<%= form_with scope: @product, url: products_path, local: true do |f| %>

<% if @product.errors.any? %>
   <div id="error_explanation">
     <h2>
       <%= pluralize(@product.errors.count, "error") %> prohibited
       this product from being saved:
     </h2>
     <ul>
       <% @product.errors.full_messages.each do |msg| %>
         <li><%= msg %></li>
       <% end %>
     </ul>
   </div>
 <% end %>

  <p>
    <strong>Name</strong><br>
    <%= f.text_field :name %>
  </p>

  <p>
    <strong>UPC</strong><br>
    <%= f.text_field :upc %>
  </p>

  <p>
    <strong>Available On</strong><br>
    <%= f.date_field :available_on %>
  </p>

  <h3>Properties</h3>
  <div id='properties'>
    <%= f.fields_for (:properties) do |property| %>
      <%= property.fields_for (:product_properties) do |product_property| %>
      <p>
        <strong>Property Name</strong><br>
        <%= property.text_field :property_name %>
      </p>

      <p>
        <strong>Property Value</strong><br>
        <%= product_property.text_field :value %>
      </p>
     <% end %>
<% end %>
  </div>


  <p>
    <%= f.submit "Add Product" %>
  </p>
<% end %>

views/products/index.html.erb

<h1>Products</h1>

<%= link_to 'New Product', new_product_path %>

<div id="search"></div>

<table>
  <tr>
    <th>Name</th>
    <th>UPC</th>
    <th>Available On</th>
    <th></th>
  </tr>

  <% @products.each do |product| %>
    <tr>
      <td><%= product.name %></td>
      <td><%= product.upc %></td>
      <td><%= product.available_on %></td>
       <% product.properties.each do |property| %>
       <td><%= property.property_name %></td>
       <% end %>
      <td><%= link_to 'Details', product_path(product) %></td>
    </tr>
  <% end %>
</table>

Answer 1

新的 form_with 结合了以前的 form_for 和 form_tag 一方面使它非常强大，但有时也很混乱。以前简单form_for @product，现在你有写

form_with model: @product, local: true do |f|

您对 scope: 的使用只是使用 @product 作为前缀，不会实际迭代或使用 @product 来查找关联，这就是为什么我们看不到 property_attributes，也不是隐含的 id 字段，即使您正确地拥有 accepts_nested_attributes（_destroy 字段将由 cocoon 的 link_to_remove_association 添加——如果您想要回到动态 add/remove 嵌套项目的能力）。

Rails 多个嵌套表单

Rails Multiple Nested Forms

ruby

ruby-on-rails

nested-forms

cocoon-gem