How to get list of ActiveStorage attributes (attachment names)?

Question

For example I have model

class User < ApplicationRecord
  has_one_attached :avatar
  has_one_attached :diploma

  has_many_attached :photos
  has_many_attached :files
end

How to get lists of attachments names for some model (separately for has_one_attached and has_many_attached)?

[:avatar, :diploma] and [:photos, :files] in this case.

Answer 1

A solution that doesn't depend on naming conventions and will give you exactly what you need based on Rails own internals:

• for has_one_attached

User
  .reflect_on_all_attachments
  .filter { |association| association.instance_of? ActiveStorage::Reflection::HasOneAttachedReflection }
  .map(&:name)

• for has_many_attached

User
  .reflect_on_all_attachments
  .filter { |association| association.instance_of? ActiveStorage::Reflection::HasManyAttachedReflection }
  .map(&:name)