Rails | Active Storage Attachment + acts_as_list

20200119064500_add_position_column_to_active_storage_attachments.rb

# db/migrate/20200119064500_add_position_column_to_active_storage_attachments.rb

class AddPositionColumnToActiveStorageAttachments < ActiveRecord::Migration[6.0]
  def change
    add_column :active_storage_attachments, :position, :integer, default: 0
  end
end

active_storage_attachment.rb

# config/initializers/active_storage_attachment.rb

module ActiveStorageAttachmentList
  extend ActiveSupport::Concern

  included do
    acts_as_list scope: [:record_id]
  end
end

Rails.configuration.to_prepare do
  ActiveStorage::Attachment.send :include, ActiveStorageAttachmentList
end

usage.rb

User.first.sorted_images.last.update(position: 1)

user.rb

# app/models/user.rb

class User < ApplicationRecord
  # Active Storage overrides to sort by position
  has_many :sorted_images, -> { order(position: :asc) }, class_name: "ActiveStorage::Attachment", as: :record, inverse_of: :record, dependent: false
end

If using on multiple models/attachments the scope should be:

acts_as_list scope: %i[record_id record_type name]

Also, just a side note: replacing has_many_attached with has_many removes a lot of dynamic methods. The has_many should also be scoped by the name of the attachment.

has_many :sorted_images, -> { where(name: "images").order(position: :asc) }, class_name: "ActiveStorage::Attachment", as: :record, inverse_of: :record, dependent: false

Was there any other sort of JavaScript used? I have been attempting something of the sort and cannot get the ajax or JavaScript to connect the position to the database. I can retrieve the position just not update the new position when moved.

Instead of rewriting that has_many just to set order, you can simply set default_scope and let original has_many_attached in model:

module ActiveStorageAttachmentList
  extend ActiveSupport::Concern

  included do
    acts_as_list scope: %i[record_id record_type name]
    default_scope { order(:position) }
  end
end