Rails Paperclip Error: No handler found for

Question

这是一个很常见的错误，我已经经历了很多答案，但没有一个对我有用。你能帮忙看看我哪里错了吗？

场景： 我有一个项目和图像 table，当用户添加一个项目时，he/she 必须至少添加一个图像。当我在附加图像后保存表单时出现错误。下面附上代码片段和错误截图：

item.rb

class Item < ApplicationRecord
  belongs_to :user, class_name: 'User', foreign_key: :user_id
  has_many :images, class_name: 'Image', foreign_key: :item_id, dependent: :destroy
  accepts_nested_attributes_for :images, allow_destroy: true
end

image.rb

class Image < ApplicationRecord
  belongs_to :item, foreign_key: :item_id, optional: true

  has_attached_file :image, styles: { small: '64x64', med: '100x100', large: '200x200' },
                    default_url: '/images/:id/:filename'
  validates_attachment_content_type :image, content_type: /\Aimage\/.*\z/
end

items_controller.rb

class ItemsController < ApplicationController

  def new
    @item = Item.new
    @item.images.build
    #new.html.erb
  end

  def create
    @item = Item.new(item_params.merge(user_id: current_user.id))
    if @item.save
      redirect_to items_path
    else
      render :new
    end
  end

  private

  def item_params
    params.require(:item).permit(:name, :category, :qty, :cost, :description,
                                 :city, :postal_code, :country,
                                 images_attributes: [:id, :item_id, :_destroy, image: []])
  end
end

new.html.erb

<div class="container">
  <h2> <% if current_user.items.blank? %> Become a seller! <% end %> Add a new item </h2> <br>
  <%= form_for @item, url: {action: :create}, html: { multipart: true } do |f| %>
      <%= item_error_messages! %>
      <div class="form-group">
        <%= f.label :name, class:'control-label col-sm-2' %>
        <div class="col-sm-10">
          <%= f.text_field :name, class: 'form-control', placeholder: 'Enter name' %>
        </div>
      </div>

      <%= f.fields_for :images, @item.images.build do |img| %>
          <%= img.file_field :image, multiple: true %>
      <% end%>

      <br><br>
      <div class="form-group">
        <div class="col-sm-offset-2 col-sm-10" style="margin-bottom: 40px;">
          <%= f.submit 'Save', class:'btn btn-default' %>
        </div>
      </div>
  <% end %>
</div>

错误：

可能是什么问题？我读过的大多数解决方案都建议在表单标签中添加 multipart: true 但它已经存在了。

谢谢

Answer 1

我认为您的问题与您试图为每个模型保存多个附加文件这一事实有关。显然，Paperclip 对这种情况的处理不是很好，所以你需要自己动手。

如果你想同时保存多个文件，你可以按照下面那个例子link中的接受答案来实现：

下面 link 的简历：

1 - To save multiple files in the above example you, do not need add multiple: true option, it will cause an error when saving.

2 - About params: This will cause an error because the model does not know what to do with an array of images

3 - To save more than one file at the same time, you need to use your own handler

Rails 4 multiple file attachments with Paperclip

祝你好运！

#更新

关于如何一次保存多个文件的想法：

1 - You will need to have a form with a dynamically input for files. So each input can get the entry for each file. You can achieve that writing your own .js lib or using a gem like "Cocoon". You will be using nested attributes here.

2 - The strong parameter in your controller will be accepting you Item model and an array of files.

3 - You will have to edit your method to save your data. E.g (in your case @item.save won't work because paperclips it's not design to accept an array of files). So, in your Item model you will have to write a method similar to the below:

(pseudo-code)

def save(item_attributes, array_of_files)
 @item = Item.new( -- add here only Item attributes --)
 @item.save

 # Here you are creating a model file for each file you are saving.
 # So there will be N file model for 1 item.
 for file in array_of_files
   @file = File.new( @item.id, file)
   @file.save
 end

 # here you can implement transaction in case a error occurs. 
 # and shows the error to your client through Item model 
 # google how to do this (transaction and Active Record class).
end

Rails Paperclip Error: No handler found for

Rails Paperclip Error: No handler found for

ruby-on-rails

ruby

paperclip