Question

I have a Category model which uses acts_as_tree

class Category < ActiveRecord::Base
  acts_as_tree :order=>"name"
end

When I display my category tree I use recursion, and an almost identical partial is generated each time (apart from some checkboxes being checked or not), requiring a large number of database calls.

I would like to cache this, but at the minute the only thing I can think of is by dumping Category.all in to a new non-ActiveRecord data structure to reduce the number of calls. Is there a better way?

index.html.erb

<%= render :partial=> "/categories/category_checkboxes", :locals=>{:select_categories=>@categories_ids} %>

_category_checkboxes.html.erb

<% @categories.each do |category| %>
    <h3><a href="#"><%=category.name%></a></h3>
    <div>
      <% category_children = category.children %>

      <%= render :partial => "/categories/category_checkbox_children",
                 :locals => { :child_categories => category_children, 
                              :chk_class=>chk_class, 
                              :select_categories=>select_categories } unless category_children.empty? %>
    </div>
<% end %>

_category_checkboxes_children.html.erb

<ul>
<% child_categories.each do |category| %>
  <li class= "category_check_box">
  <%=check_box_tag("category#{category.id}", 1, select_categories.index(category.id)%>
  <%=label_tag("category#{category.id}" ,"#{category.name}")%>
  <%= render :partial => "/categories/category_checkbox_children",  :locals => { 
                          :child_categories => category.children,
                          :select_categories=>select_categories} unless category_children.empty? %>
<% end %>
</li>
</ul>

Answer 1

The acts_as_tree gem is rather out of date. The last version (0.1.1) is from February 2010, and its functionality pretty limited.

I recommend you take a look at ancestry, a gem that provides similar functionality, and has added much more. Specifically, take a look at the section on Selecting nodes by depth.