Rails Activerecord，嵌套验证

Question

我已经担心这个错误太多天了，我不确定我错过了什么。

我有一个名为“product”的父模型和一个名为“product_attachment”的子模型。 通过 /product_attachments#new

在创建时成功验证子模型以禁止空白图像字段

但是，当使用其父表单 /product#new（以下文件）时，我希望它能够在没有图像的情况下成功验证失败。但是，Activerecord 忽略了错误，如果验证通过然后抱怨我的 product_attachments 为空，我的控制器会尝试保存结果。

我目前的理解是，使用“validates_associated”将验证子模型作为父进程的一部分，但这并没有奏效。 我们没有在表单中传递一个快乐的失败验证以允许用户采取行动，而是离开表单，控制器尝试处理由于没有附件而失败的 create 方法。 由于我应该始终有附件，因此一直试图修复此验证无济于事。

感谢您的帮助，我之前已包含类似的代码示例以供您提供反馈。 我对 Rails 很陌生，所以我希望我误用了关键语法或上下文。

我也很好奇是什么原因以及最好的解决方法是什么，因为我仍在开发良好的调试实践。

产品.rb

class Product < ActiveRecord::Base

  has_many :product_attachments
  validates_presence_of :title, :message =>  "You must provide a name for this product."
  accepts_nested_attributes_for :product_attachments, allow_destroy: true#, 
  validates_associated :product_attachments
end

product_attachment.rb （这里使用carrierwave来处理上传，似乎工作正常）

class ProductAttachment < ActiveRecord::Base
  belongs_to :product 
  mount_uploader :image, ImageUploader
  validates_presence_of :image, :message =>  "You must upload an image to go with this item."
end

products_controller.rb

class ProductsController < ApplicationController
  before_action :set_product, only: [:show, :edit, :update, :destroy]

  def index
    @products = Product.all
  end

  def show
    @product_attachments = @product.product_attachments.all
  end

  def new
    @product = Product.new
    @product_attachment = @product.product_attachments.build
  end

  def edit
  end

  def create
    @product = Product.new(product_params)
    respond_to do |format|
      if @product.save
        params[:product_attachments]['image'].each do |a|
          @product_attachment = @product.product_attachments.create!(:image => a)
        end
        format.html { redirect_to @product, notice: 'Product was successfully created.' }
      else #- when would this fire?
        format.html { render :new }
      end
    end
  end

  def update
    respond_to do |format|
      if @product.update(product_params)
          params[:product_attachments]['image'].each do |a|
            @product_attachment = @product.product_attachments.create!(:image => a, :post_id => @post.id)
          end
        format.html { redirect_to @product, notice: 'Product was successfully updated.' }
      else #- when would this fire?
        format.html { render action: 'new' }
      end
    end
  end

  def destroy
    @product.destroy
    respond_to do |format|
      format.html { redirect_to @product, notice: 'Product was successfully destroyed.' }
    end
  end

  private
    def set_product
      @product = Product.find(params[:id])
    end
    # we pass the _destroy so the above model has the access to delete
    def product_params
      params.require(:product).permit(:id, :title, :price, :barcode, :description, product_attachment_attributes: [:id, :product_id, :image, :filename, :image_cache, :_destroy])
    end

end

product_attachments_controller.rb

class ProductAttachmentsController < ApplicationController
  before_action :set_product_attachment, only: [:show, :edit, :update, :destroy]

  def index
    @product_attachments = ProductAttachment.all
  end

  def show
  end

  def new
    @product_attachment = ProductAttachment.new
  end

  def edit
  end

  def create
    @product_attachment = ProductAttachment.new(product_attachment_params)

    respond_to do |format|
      if @product_attachment.save
        @product_attachment.image = params[:image]
        format.html { redirect_to @product_attachment, notice: 'Product attachment was successfully created.' }
      else
        format.html { render :new }
      end
    end
  end

  def update
    respond_to do |format|
      if @product_attachment.update(product_attachment_params)
        @product_attachment.image = params[:image]
        format.html { redirect_to @product_attachment.product, notice: 'Product attachment was successfully updated.' }
      else
        format.html { render :edit }
      end
    end
  end

  def destroy
    @product_attachment.destroy
    respond_to do |format|
      format.html { redirect_to product_attachments_url, notice: 'Product attachment was successfully destroyed.' }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_product_attachment
      @product_attachment = ProductAttachment.find(params[:id])
    end

    def product_attachment_params
      params.require(:product_attachment).permit(:id, :product_id, :image, :image_cache)
    end
end

_form.html.slim （这里使用 simple_form + slim + cocoon...）

= simple_form_for @product do |f|

  - if @product.errors.any?
    #error_explanation
      h2
        = pluralize(@product.errors.count, "error")
        |  prohibited this product from being saved:
      ul 
        - @product.errors.each do |attribute, message|
          - if message.is_a?(String)
            li= message

  = f.input :title
  = f.input :price, required: true
  = f.input :barcode
  = f.input :description

  h3 attach product images
  #product_attachment
    = f.simple_fields_for :product_attachments do |product_attachment|
      = render 'product_attachment_fields', f: product_attachment
    .links
      = link_to_add_association 'add product attachment', f, :product_attachments
  = f.submit

_product_attachment_fields.html.slim 注意到我需要以这种方式命名我的文件字段，以便我的控制器正确使用文件，但仍然不确定为什么。

.nested-fields
  = f.file_field :image , :multiple => true , name: "product_attachments[image][]"
  = link_to_remove_association "remove", f

如果我能提供其他任何东西，请告诉我。

感谢您抽出宝贵时间阅读/回复。

Edit1: 在撰写本文时，我目前的调试方法是剥离代码块并通过浏览器测试功能。我读过我应该更熟悉 Rails 控制台，但还没有到那里。

编辑2：

undefined method `[]' for nil:NilClass

        params[:product_attachments]['image'].each do |a|


app/controllers/products_controller.rb:47:in `block in create'
app/controllers/products_controller.rb:44:in `create'

Request

Parameters:

{"utf8"=>"✓",
 "authenticity_token"=>"{mytoken}",
 "product"=>{"title"=>"pleasefailwell",
 "commit"=>"Create Product"}

Edit3：为了清晰起见，对原始部分进行了重新措辞

Answer 1

看到您的最新编辑，我认为这正在发生，这意味着 product_attachments 为零。这是正确的，参数应该是product_attachments_attributes。

这会导致您的 product_params 方法出现另一个问题。

你有product_attachment_attributes，基本形式“字段”应该是复数形式：product_attachments_attributes

简而言之：

从控制器中移除产品附件环。修复 strong params 方法，之后应该可以工作了。

编辑：

同时从file_field 中删除name 属性，这没有帮助。