active_storage_dryable.rb

module Attachable
  extend ActiveSupport::Concern

  included do
    ## -------------------- Associations -------------------- ##
    if const_defined?('STORAGE_TYPES')
      self::STORAGE_TYPES.each do |k, v|
        v == :one ? has_one_attached(k.to_sym) : has_many_attached(k.to_sym)
      end
    end

    ## ---------------------- Methods ----------------------- ##
    if const_defined?('STORAGE_TYPES')
      self::STORAGE_TYPES.each do |name, v|
        define_method("#{name}_url") do
          if v == :one
            send(name).attached? ? send(name).service_url : default_attach
          else
            send(name).map(&:service_url)
          end
        end
      end
    end
  end

  # Override it if the model has no default attach
  def default_attach?
    true
  end

  def config
    Rails.application.secrets.slice(:host, :http_type)
  end

  def default_attach
    "#{config[:http_type]}://#{config[:host]}/images/missing.png" if default_attach?
  end
end

# Usage:
# Include the concern and setup the constant as defined below
# STORAGE_TYPES = {img: :one,  files: :many, file: :one}

class User < ApplicationRecord
  STORAGE_TYPES = {img: :one,  files: :many, file: :one}
  include Attachable
end

user = User.first
user.files.attach(io: File.open("/Users/majed/Majeddocs/majed.jpeg"), filename: "majed.jpeg", content_type: "image/jpg")
user.files_url # Array of attach URLS

user.img.attach(io: File.open("/Users/majed/Majeddocs/majed.jpeg"), filename: "majed.jpeg", content_type: "image/jpg")
user.img_url # URL as String