Rails 5.2 Active Storage add custom attributes

If you need to store additional data with each image and perform queries based on that data, I’d recommend extracting an Image model that wraps an attached file:

# app/models/project.rb
class Project < ApplicationRecord
  has_many :images, dependent: :destroy
end

# app/models/image.rb
class Image < ApplicationRecord
  belongs_to :project

  has_one_attached :file
  delegate_missing_to :file

  scope :positioned, -> { order(position: :asc) }
end

<%# app/views/projects/show.html.erb %>
<% @project.images.positioned.each do |image| %>
  <%= image_tag image %>
<% end %>

Note that the example view above causes 2N+1 queries for a project with N images (one query for the project’s images, another for each image’s ActiveStorage::Attachment record, and one more for each attached ActiveStorage::Blob). I deliberately avoided optimizing the number of queries for clarity’s sake.