如何在更新模型时验证关联对象编号

Question

无法理解如何在更新主模型时验证关联模型的大小。在我的应用产品中，附加图片不能超过 6 张。我存储在 ProductAttachment 类中的每张图片

product.rb

class Product < ActiveRecord::Base
belongs_to :user
has_many :product_attachments, dependent: :destroy
accepts_nested_attributes_for :product_attachments
validate :validate_attachments_count


  def validate_attachments_count
    if self.product_attachments.size > 6
      errors.add(:product_attachments, 'Pic number should not be more than 6')
    end
  end
end

product_attachment.rb

class ProductAttachment < ActiveRecord::Base
mount_uploader :picture, PictureUploader
belongs_to :product
after_destroy :delete_picture

private
  def delete_picture
    self.remove_picture!
  end
end  

在 products_controller 我有一个创建方法

def create
  @product = current_user.products.new(products_params)
  # if pics available add attachments
  if params[:product_attachments] != nil
    params[:product_attachments]['picture'].each do |p|
      @product_attachment = @product.product_attachments.build(:picture => p)
    end
  end
  if @product.save
      flash[:success] = 'Product created.'
      redirect_to [current_user, @product]
  else
      flash[:danger] = 'Product not created'
      render 'new'
  end
end

如果我尝试附加 6 张以上的图片，它工作正常并且创建被拒绝，但是更新方法无法以某种方式确定附件的数量并允许添加任意数量的图片

def update
  if @product.update_attributes(products_params)
    if params[:product_attachments] != nil
      params[:product_attachments]['picture'].each do |p|
        @product_attachment = @product.product_attachments.create(:picture => p)
      end
    end
    flash[:success] = 'Info updated.'
    redirect_to [current_user, @product]
  else
    flash[:danger] = 'Can't update'
    render :edit
  end
end 

我想我应该更改 products_params 方法中的某些内容，但我无法弄清楚到底是什么

def products_params
  params.require(:product).permit(:name, :width, :height, :depth, :color, :price, :category, :description,
  product_attachments_attributes: [:id, :product_id, :picture, :remove_picture])
end     

这是一个表格

<div class="form-group">
    <% if @product.new_record? %>
      <%= f.fields_for :product_attachments do |p| %>
        <div class="control-label col-md-4">
          <%= p.label :picture, 'Pictures' %>
        </div>
        <div class="col-md-4">
          <%= p.file_field :picture, multiple: true, name: 'product_attachments[picture][]' %>
        </div>
      <% end %>
    <% else %>
        <div class="control-label col-md-4"><strong>Pictures</strong></div>
        <div class="col-md-4">
          <% @product.product_attachments.each do |p| %>
            <%= image_tag p.picture_url, class: 'pic' %>
            <%= link_to 'Delete', product_attachment_path(p),
                        method: :delete , data: { confirm: 'Sure?'} %>
          <% end %>
          <%= f.fields_for :product_attachments, @product.product_attachments.new do |p| %>
            <div class="col-md-4">
              <%= p.file_field :picture, multiple: true, name: 'product_attachments[picture][]' %>
            </div>
          <% end %>
        </div>
    <% end %>
  </div>

Answer 1

您可以通过在#update 的快乐路径中显式添加@product.save 调用来手动触发该验证。