Can't upload image

My code when upload image
class DataFile < ActiveRecord::Base
def self.save(upload)
name = upload[‘datafile’].original_filename
directory = “public/free”
# create the file path
path = File.join(directory, name)
# write the file
File.open(path, “wb”) { |f| f.write(upload[‘datafile’].read) }
end
end
but i upload image have name: image1.jpg is it show : undefined method
`original_filename’ for “images2.jpg”:String

I repaired because a multi-part form. Add :multipart=> true to my
form_tag.