<% is_single = d.book.data.count == 1 btn_class = is_single ? "btn btn-success" : nil %> <%= link_to book_data_path(id: d.book, data_format: d.format), class: btn_class do %> <% if is_single %> Download <% end %> <%= d.format %> (<%= number_to_human_size(d.uncompressed_size) %>) <% end %>