*Rails Beginner* Txt file upload to filesystem + DB

class Document < ActiveRecord::Base
        attr_accessible :body, :extension, :filename, :upload

        def upload=(incoming_file)
                        unless incoming_file.blank?
                        @incoming_file = incoming_file
              self.filename = incoming_file.original_filename
        self.extension = incoming_file.original_filename.split('.').last.downcase
                                if self.extension == 'txt'
                self.body = incoming_file.read
                                else
                                        self.body = 'wrong file type for direct uploading'
                                end
                        end
    end

#    def filename=(new_filename)
#        write_attribute("filename", sanitize_filename(new_filename))
#    end

    # File.join is a cross-platform way of joining directories;
    # we could have written "#{Rails.root}/public/doc_store"
    DOC_STORE = File.join Rails.root, 'public', 'doc_store'

     # where to write the first file to
    def document_filename
      File.join DOC_STORE, "#{id}.#{extension}"
    end

    # where to write the txt file to
    def document_txtfilenamehas_document
      File.join DOC_STORE, "#{id}.txt"
    end

    # return a path we can use in HTML for the docfile
    def document_html_path
      "/doc_store/#{id}.#{extension}"
    end

    # if a doc file exists, then we has a docfile
    def has_document?
      File.exists? document_filename
    end

after_save :store_doc

    private

                def store_doc
                logger.info "NOW inside store_doc"
                        if @incoming_file
                                #make the DOCSTORE dir if it doesn't already exist
                                FileUtils.mkdir_p DOC_STORE
                                #write out the data to the file
                                logger.info "write out the data to the file"
                                File.open(document_filename, 'wb') do |f|
                                        f.write(@incoming_file.read)
                                end

#                               @incoming_file = nil
                        end
                end

end