Upload file from ruby on rails program with paperclip gem

gistfile1.rb

# MyModel Model
class MyModel < ActiveRecord::Base
    
    has_attached_file :my_image,
      :styles => {  :small_thumb    => "50x50",
                    :medium_thumb   => "100x100" 
                 },
      :default_url  => "/images/missing/prints/:style.png"
end


# Ruby code to upload/push the image into MyModel Model and create the images of different sizes
my_model_obj = MyModel.new
my_model_obj.my_image = File.open('file/path')
my_model_obj.save!