Carrier wave for multiple Uploads

_form.html.erb

<%= form_for(@user, multiple: true) do |f| %>
  ...
  
  <div class="field">
    <%= f.label :images %><br>
    <%= f.file_field :images, multiple: true %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
  
  ....
  
<% end %>

Gemfile

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

images_uploader.rb

# app/uploaders/image_uploarder.rb
class ImageUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
  # include CarrierWave::RMagick
  # include CarrierWave::MiniMagick

  # Choose what kind of storage to use for this uploader:
  storage :file
  # storage :fog

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process scale: [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end

  # Create different versions of your uploaded files:
  # version :thumb do
  #   process resize_to_fit: [50, 50]
  # end

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  # def extension_whitelist
  #   %w(jpg jpeg gif png)
  # end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end

user.rb

# app/models/user.rb
class User < ActiveRecord::Base
    # note that mount_uploaders need to be in plural, as well as the :images attribute
    mount_uploaders :images, ImageUploader
    
    # serialize is required for sqlite3
    serialize :images, Array
end

#
# migration
def change
  add_column :users, :images, :json
  # :json creates problems generating schema.rb for sqlite3. you can use :text instead
end