Carrierwave, Rails 4, and Multiple Uploads - ruby-on-rails

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.

Answer 3

I would create a model called Documents with a field that's mounted
class Documents < ActiveRecord::Base
belongs_to :transcription
mount_uploader :doc, DocumentUploader
end
class Transcriptions < ActiveRecord::Base
has_many :documents
end
And I would still have user the below line in my controller:
params.require(:transcription).permit(..... , { document: [] })

Answer 4

The best method for this that I have come across is using the native approach of CarrierWave. If you already have single file upload done, with the native approach it takes less than 5 minutes to get multiple file upload. https://github.com/carrierwaveuploader/carrierwave#multiple-file-uploads