Carrierwave, Rails 4, and Multiple Uploads

Question

I have been banging my head against the wall trying to get Carrierwave, Rails 4, and Multiple Uploads all working together. I can get a single file upload working just fine as in this and many other projects.

This is not a nested situation - just simply uploading to a single model called Transcription and wanting to create a record for each document uploaded.

I cannot seem to find the correct way to declare the "document" field used for the carrierwave mount

mount_uploader :document, DocumentUploader

as an array for the strong parameters to recognize.

I have tried whitelisting: whitelisted[:document] = params[:transcription]['document'],

declaring the "document" as an array:

params.require(:transcription).permit(..... ,:document => [])

params.require(:transcription).permit(..... , { document: [] })

This all seems more like I am declaring the array for a nested model, but I really want Rails 4's strong parameters to simply see the "document" array created by the file_field, :multiple => true

ie. from the log: form-data; name=\"transcription[document][]

Has anybody successfully accomplished multiple uploads in Rails 4 with strong parameters? If so would you please share?

Thanks...

Cheers,

Bill

Answer 1

This is solution to upload multiple images using carrierwave in rails 4 from scratch

To do just follow these steps.

rails new multiple_image_upload_carrierwave

In gem file

gem 'carrierwave'
bundle install
rails generate uploader Avatar 

Create post scaffold

rails g scaffold post title:string

Create post_attachment scaffold

rails g scaffold post_attachment post_id:integer avatar:string

rake db:migrate

In post.rb

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

In post_attachment.rb

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

In post_controller.rb

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, :post_id => @post.id)
       end
       format.html { redirect_to @post, notice: 'Post was successfully created.' }
     else
       format.html { render action: 'new' }
     end
   end
 end

 def update
   respond_to do |format|
     if @post.update(post_params)
       params[:post_attachments]['avatar'].each do |a|
         @post_attachment = @post.post_attachments.create!(:avatar => a, :post_id => @post.id)
       end
     end
  end

  def destroy
    @post.destroy
    respond_to do |format|
      format.html { redirect_to @post }
      format.json { head :no_content }
    end
  end


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

In views/posts/_form.html.erb

<%= 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 %>

   <% if params[:controller] == "post" && params[:action] == "edit" %> 
     <% @post.post_attachments.each do |p| %>
       <%= image_tag p.avatar, :size => "150x150" %>
     <% end %>
   <% end %>

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

In views/posts/show.html.erb

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

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

<% @post_attachments.each do |p| %>
  <%= image_tag p.avatar_url, :size => "150x150" %>
  <%= link_to "Destroy", p, method: :delete %>
<% end %>

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

In rails 3 no need to define strong parameters and as you can define attribute_accessible in both the model and accept_nested_attribute to post model because attribute accessible is deprecated in rails 4.

Answer 2

CarrierWave doesn't support multiple uploads. It's designed to associate a single file with a single field.

If you want multiple uploads, you need either multiple fields (each with a CarrierWave uploader), or multiple objects each with a single CarrierWave uploader field.

The multiple attribute is also unsupported, so if you use it, it's entirely up to you to get the parameters assigned properly.