Rails: concern doesn't load has_one child

Question

If I have a parent class like so:

class Component < ApplicationRecord
  include Imageable
end

And that concern looks like so:

module Imageable
  extend ActiveSupport::Concern

  included do
    has_one :image_attachment, as: :imageable, dependent: :destroy
  end
end

And that class looks like this:

class ImageAttachment < ApplicationRecord
  belongs_to :imageable, polymorphic: true, optional: true

  has_attached_file :data
end

Why can't they find each other given these two instances?

ImageAttachment.last
 => <ImageAttachment id: 12, imageable_type: "component", imageable_id: 3, data_file_name: "tumblr_nb88njd2DF1sfwp0ho1_1280.jpg", data_content_type: "image/jpeg", data_file_size: 63794, data_updated_at: "2018-05-02 11:07:12", created_at: "2018-05-02 10:37:48", updated_at: "2018-05-02 11:07:13">

Component.find(3)
=> <Component id: 3, name: "Testing", body: "Test body", created_at: "2017-11-22 02:43:03", updated_at: "2018-05-01 23:50:01">

Component.find(3).image_attachment
=> nil

ImageAttachment.last.component
=> NoMethodError (undefined method `component' for #<ImageAttachment:0x00007fea291ac1e0>)

Answer 1

1) It seems that your imageable_type attribute is wrong, because it should be a class name e.g. 'Component' not 'component'. Rails would not do this by default, so I assume you tampered with that column manually and that is why it is not working

2) ImageAttachment.last.component -> this won't work because your association for ImageAttachment is belongs_to :imageable, so in order to get parent, you need to call ImageAttachment.last.imageable