base64_image_str_to_file.rb

def process_logo_data_uri
  if self.logo_data_uri && !self.logo_data_uri.split(",").last.nil?
    data = StringIO.new(Base64.decode64(self.logo_data_uri))
    data.class_eval do
      attr_accessor :content_type, :original_filename
    end
 
    data.content_type       = self.logo_data_uri.match(/image\/[a-z]{3,}/i).to_s
    data.original_filename  = "image_name.#{data.content_type.to_s}"
 
    self.logo = data
  end    
end