def destroy
  @book = Book.find(params[:id])

  respond_to do |format|
    if @book.destroy
      format.html { redirect_to books_url, notice: "Book was successfully deleted." }
    else
      format.html do
        error_messages = @book.errors.try(:messages)
        error_messages = error_messages[:base].join('. ') + '.' if error_messages.present?
        flash[:error] = "Book deletion failed. #{ error_messages }"
        redirect_to books_url
      end
    end
    format.json { head :no_content } # what should this be?
  end
end