PaperClip for Two Models Error? - ruby-on-rails

Question

I installed Paperclip for my first Model and its working fine but when i try to add it to my second Model i get an error . I am basically trying to have two image uploading for my two Models that i have created. This is the Error:
undefined method `image_content_type' for #<IosCourse:0x007fd4bb3bfaf0>
This is my first model (Rubycourse.rb):
class Rubycourse < ActiveRecord::Base
acts_as_votable
has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }, :default_url => "/images/:style/missing.png"
validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
has_many :reviews
end
This is the second model (IosCourse.rb):
class IosCourse < ActiveRecord::Base
attr_accessor :image_file_name
has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }, :default_url => "/images/:style/missing.png"
validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
end

Answer 1

You should add the needed columns (for Paperclip) to the second model as well.
Paperclip will wrap up to four attributes (all prefixed with that attachment's name, so you can have multiple attachments per model if you wish) and give them a friendly front end. These attributes are:
|attachment|_file_name
|attachment|_file_size
|attachment|_content_type
|attachment|_updated_at
So, basically you need to write/run a migration to add those attributes to the second model:
class AddImageColumnsToIosCourse < ActiveRecord::Migration
def self.up
add_attachment :ios_courses, :image
end
def self.down
remove_attachment :ios_courses, :image
end
end
Paperclip provides a migration generator to generate that file:
$ rails generate paperclip IosCourse image
Another idea: If you'll have different models with attachments, and these attachments will have similar logic (validations, extra methods, ...), it's probably a good idea to create a polymorphic model (ie. Attachment) with all these Paperclip logic and associate this new model with the rest of your models.
class Attachment < ActiveRecord::Base
belongs_to :attachable, polymorphic: true
# Paperclip stuff
has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }, :default_url => "/images/:style/missing.png"
validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
end
class Rubycourse < ActiveRecord::Base
has_one :attachment, as: :attachable
end
class IosCourse < ActiveRecord::Base
has_one :attachment, as: :attachable
end