tag treeをcache

app/helpers/posts_helper.rb

@@ -3,7 +3,9 @@ module PostsHelper
   # @param {ActiveRecord::Relation} node
   def h_display_tree(node)
     _html = '<ul>'
-    _html << %Q{<li><a href="#{ root_path(q: '#' + node.name) }">#{node.name} <span class="badge">#{node.post_tags.count}</span></a></li>}
+    if node.posts.count > 0
+      _html << %Q{<li><a href="#{ root_path(q: '#' + node.name) }">#{node.name} <span class="badge">#{node.posts.count}</span></a></li>}
+    end
     node.children.each do |_child|
       _html << h_display_tree(_child)
     end

app/views/posts/index.html.erb

@@ -15,11 +15,13 @@
           <% end %>
         </div>
 
+        <% cache('tag-tree', :expires_in => 1.hour) do %>
           <div class="list-group">
             <% Tag.roots.each do |root| %>
               <%= h_display_tree(root) %>
             <% end %>
           </div>
+        <% end %>
 
       </div><!--/span-->