0条消息则不显示“全部设为已读”

app/views/users/user_messages.html.erb

@@ -31,7 +31,10 @@
 <div>
 <% if params[:type].nil? %>
     <div class="newsReadSetting">
-        有&nbsp;<span class="c_red"><%= User.current.count_new_message %></span>&nbsp;条未读<a href="javascript:void(0);" class="ml15"><%= link_to "全部设为已读", user_message_path(User.current, :viewed => 'all') %></a>
+        有&nbsp;<span class="c_red"><%= User.current.count_new_message %></span>&nbsp;条未读
+      <% unless User.current.count_new_message == 0 %>
+        <a href="javascript:void(0);" class="ml15"><%= link_to "全部设为已读", user_message_path(User.current, :viewed => 'all') %></a>
+      <% end %>
     </div>
 <% end %>
 <% if @message_alls.count >0 %>