Rails 4使用carrierwave上传多个图像或文件

Question

如何使用 Rails 4 和 CarrierWave 从文件选择窗口上传多个图像？我有一个 post_controller 和 post_attachments 模型。我该怎么做？

有人可以举个例子吗？有没有简单的方法？

Answer 1

这是使用 rails 4 中的载波从头开始上传多个图像的解决方案

或者你可以找到工作演示： Multiple Attachment Rails 4

只需按照以下步骤操作即可。

rails new multiple_image_upload_carrierwave

在 gem 文件中

gem 'carrierwave'
bundle install
rails generate uploader Avatar 

创建脚手架

rails generate scaffold post title:string

创建 post_attachment 脚手架

rails generate scaffold post_attachment post_id:integer avatar:string

rake db:migrate

在 post.rb 中

class Post < ActiveRecord::Base
   has_many :post_attachments
   accepts_nested_attributes_for :post_attachments
end

在 post_attachment.rb 中

class PostAttachment < ActiveRecord::Base
   mount_uploader :avatar, AvatarUploader
   belongs_to :post
end

在 post_controller.rb 中

def show
   @post_attachments = @post.post_attachments.all
end

def new
   @post = Post.new
   @post_attachment = @post.post_attachments.build
end

def create
   @post = Post.new(post_params)

   respond_to do |format|
     if @post.save
       params[:post_attachments]['avatar'].each do |a|
          @post_attachment = @post.post_attachments.create!(:avatar => a)
       end
       format.html { redirect_to @post, notice: 'Post was successfully created.' }
     else
       format.html { render action: 'new' }
     end
   end
 end

 private
   def post_params
      params.require(:post).permit(:title, post_attachments_attributes: [:id, :post_id, :avatar])
   end

在views/posts/_form.html.erb中

<%= form_for(@post, :html => { :multipart => true }) do |f| %>
   <div class="field">
     <%= f.label :title %><br>
     <%= f.text_field :title %>
   </div>

   <%= f.fields_for :post_attachments do |p| %>
     <div class="field">
       <%= p.label :avatar %><br>
       <%= p.file_field :avatar, :multiple => true, name: "post_attachments[avatar][]" %>
     </div>
   <% end %>

   <div class="actions">
     <%= f.submit %>
   </div>
<% end %>

编辑任何帖子的附件和附件列表。 在views/posts/show.html.erb中

<p id="notice"><%= notice %></p>

<p>
  <strong>Title:</strong>
  <%= @post.title %>
</p>

<% @post_attachments.each do |p| %>
  <%= image_tag p.avatar_url %>
  <%= link_to "Edit Attachment", edit_post_attachment_path(p) %>
<% end %>

<%= link_to 'Edit', edit_post_path(@post) %> |
<%= link_to 'Back', posts_path %>

更新表单以编辑附件views/post_attachments/_form.html.erb

<%= image_tag @post_attachment.avatar %>
<%= form_for(@post_attachment) do |f| %>
  <div class="field">
    <%= f.label :avatar %><br>
    <%= f.file_field :avatar %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

修改post_attachment_controller.rb中的更新方法

def update
  respond_to do |format|
    if @post_attachment.update(post_attachment_params)
      format.html { redirect_to @post_attachment.post, notice: 'Post attachment was successfully updated.' }
    end 
  end
end

在 rails 3 中无需定义强参数，您可以在模型中定义 attribute_accessible 并在模型中定义 accept_nested_attribute 来发布模型，因为在 rails 4 中不推荐使用属性可访问性。

对于编辑附件，我们不能一次修改所有附件。所以我们会一一替换附件，或者你可以根据你的规则修改，这里我只是告诉你如何更新任何附件。

Answer 2

如果我们看一下 CarrierWave 的文档，现在这实际上非常简单。

https://github.com/carrierwaveuploader/carrierwave/blob/master/README.md#multiple-file-uploads

我将使用Product作为我要添加图片的模型，作为示例。

1. 获取主分支 Carrierwave 并将其添加到您的 Gemfile：

   gem 'carrierwave', github:'carrierwaveuploader/carrierwave'
   

2. 在预期模型中创建一个列来托管图像数组：

   rails generate migration AddPicturesToProducts pictures:json
   

3. 运行迁移

   bundle exec rake db:migrate
   

4. 为模型产品添加图片

   app/models/product.rb
   
   class Product < ActiveRecord::Base
     validates :name, presence: true
     mount_uploaders :pictures, PictureUploader
   end
   

5. 在 ProductsController 中为强参数添加图片

   app/controllers/products_controller.rb
   
   def product_params
     params.require(:product).permit(:name, pictures: [])
   end
   

6. 允许您的表单接受多张图片

   app/views/products/new.html.erb
   
   # notice 'html: { multipart: true }'
   <%= form_for @product, html: { multipart: true } do |f| %>
     <%= f.label :name %>
     <%= f.text_field :name %>
   
     # notice 'multiple: true'
     <%= f.label :pictures %>
     <%= f.file_field :pictures, multiple: true, accept: "image/jpeg, image/jpg, image/gif, image/png" %>
   
     <%= f.submit "Submit" %>
   <% end %>
   

7. 在您的视图中，您可以引用解析图片数组的图像：

   @product.pictures[1].url
   

如果您从一个文件夹中选择多个图像，则顺序将与您从上到下的确切顺序相同。

Answer 3

SSR 答案的一些小补充：

accepts_nested_attributes_for 不需要您更改父对象的控制器。所以如果要纠正

name: "post_attachments[avatar][]"

到

name: "post[post_attachments_attributes][][avatar]"

那么像这样的所有这些控制器更改都变得多余：

params[:post_attachments]['avatar'].each do |a|
  @post_attachment = @post.post_attachments.create!(:avatar => a)
end

您还应该在父对象表单中添加PostAttachment.new：

在views/posts/_form.html.erb中

  <%= f.fields_for :post_attachments, PostAttachment.new do |ff| %>
    <div class="field">
      <%= ff.label :avatar %><br>
      <%= ff.file_field :avatar, :multiple => true, name: "post[post_attachments_attributes][][avatar]" %>
    </div>
  <% end %>

这会使父控制器中的这种更改变得多余：

@post_attachment = @post.post_attachments.build

欲了解更多信息，请参阅Rails fields_for form not showing up, nested form

如果你使用 Rails 5，那么由于 accepts_nested_attributes_for 中的错误（否则 accepts_nested_attributes_for 一般不能在 Rails 5 下工作）。

编辑 1：

添加关于destroy：

在models/post.rb中

class Post < ApplicationRecord
    ...
    accepts_nested_attributes_for :post_attachments, allow_destroy: true
end

在views/posts/_form.html.erb中

 <% f.object.post_attachments.each do |post_attachment| %>
    <% if post_attachment.id %>

      <%

      post_attachments_delete_params =
      {
      post:
        {              
          post_attachments_attributes: { id: post_attachment.id, _destroy: true }
        }
      }

      %>

      <%= link_to "Delete", post_path(f.object.id, post_attachments_delete_params), method: :patch, data: { confirm: 'Are you sure?' } %>

      <br><br>
    <% end %>
  <% end %>

这样，您根本就不需要拥有子对象的控制器！我的意思是不再需要任何PostAttachmentsController。至于父对象的控制器 (PostController)，您也几乎不会更改它 - 您唯一更改的是白名单参数列表（包括与子对象相关的参数) 像这样：

def post_params
  params.require(:post).permit(:title, :text, 
    post_attachments_attributes: ["avatar", "@original_filename", "@content_type", "@headers", "_destroy", "id"])
end

这就是accepts_nested_attributes_for 如此神奇的原因。

Answer 4

我还想出了如何更新多文件上传，我还对其进行了一些重构。这段代码是我的，但你明白了。

def create
  @motherboard = Motherboard.new(motherboard_params)
  if @motherboard.save
    save_attachments if params[:motherboard_attachments]
    redirect_to @motherboard, notice: 'Motherboard was successfully created.'
  else
    render :new
  end
end


def update
  update_attachments if params[:motherboard_attachments]
  if @motherboard.update(motherboard_params)
    redirect_to @motherboard, notice: 'Motherboard was successfully updated.'
  else
   render :edit
  end
end

private
def save_attachments
  params[:motherboard_attachments]['photo'].each do |photo|
    @motherboard_attachment = @motherboard.motherboard_attachments.create!(:photo => photo)
  end
end

 def update_attachments
   @motherboard.motherboard_attachments.each(&:destroy) if @motherboard.motherboard_attachments.present?
   params[:motherboard_attachments]['photo'].each do |photo|
     @motherboard_attachment = @motherboard.motherboard_attachments.create!(:photo => photo)
   end
 end

Answer 5

这是我对模型的第二次重构：

1. 将私有方法移至模型。
2. 将@motherboard 替换为self。

控制器：

def create
  @motherboard = Motherboard.new(motherboard_params)

  if @motherboard.save
    @motherboard.save_attachments(params) if params[:motherboard_attachments]
  redirect_to @motherboard, notice: 'Motherboard was successfully created.'
  else
    render :new
  end
end

def update
  @motherboard.update_attachments(params) if params[:motherboard_attachments]
  if @motherboard.update(motherboard_params)
    redirect_to @motherboard, notice: 'Motherboard was successfully updated.'
  else
    render :edit
  end
end

在主板型号中：

def save_attachments(params)
  params[:motherboard_attachments]['photo'].each do |photo|
    self.motherboard_attachments.create!(:photo => photo)
  end
end

def update_attachments(params)
  self.motherboard_attachments.each(&:destroy) if self.motherboard_attachments.present?
  params[:motherboard_attachments]['photo'].each do |photo|
    self.motherboard_attachments.create!(:photo => photo)
  end
end

Answer 6

使用@post.post_attachments关联时，不需要设置post_id。