Pre-defined ActiveStorage variants in Rails 7.1

Rails 7.1 adds the ability to use pre-defined variants when calling preview or representation on an attachment.

class User < ActiveRecord::Base
  has_one_attached :file do |attachable|
    attachable.variant :thumb, resize_to_limit: [100, 100]
  end
end

<%= image_tag user.file.representation(:thumb) %>

Here, we declare a thumb variant that can later be referenced—no need to explicitly express the resize_to_limit directly at the image_tag call.