ruby on rails - PaperClip for Two Models Error? -

i installed paperclip first model , working fine when try add second model error . trying have 2 image uploading 2 models have created. error:

undefined method `image_content_type' #<ioscourse:0x007fd4bb3bfaf0> 

this 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 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 

you should add needed columns (for paperclip) second model well.

paperclip wrap 4 attributes (all prefixed attachment's name, can have multiple attachments per model if wish) , give them friendly front end. these attributes are:

• |attachment|_file_name
• |attachment|_file_size
• |attachment|_content_type
• |attachment|_updated_at

so, need write/run migration add attributes 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 migration generator generate file:

$ rails generate paperclip ioscourse image  

another idea: if you'll have different models attachments, , these attachments have similar logic (validations, methods, ...), it's idea create polymorphic model (ie. attachment) these paperclip logic , associate new model rest of 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