title: Rails 3 Meta_Search Multi-level associations
body: <p>I have the following classes </p>
  
  <pre><code>class BusinessLocation
    has_many :campaigns
  end
  </code></pre>
  
  <p>My campaigns class as an attribute called event_return_rate.  I am using meta_search's sort_link url helper to sort a list of Business_Locations using the following format:</p>
  
  <pre><code>  &lt;%= sort_link @search, :average_price, "Avg. Menu Price" %&gt;
    &lt;%= sort_link @search, :temp_return_rate, "% of Sale" %&gt;
  </code></pre>
  
  <p>In order to get the sorting to work, i had to create a temp_return_rate attribute in my BusinessLocations to sort it using the sort_link helper.  I would like to know if there is a way to do this without having to create a temp attribute in my BusinessLocations class.</p>
  
  <p>Also since there are many campaigns associated with my BusinessLocation, when I need the query to return campaign who's end_date > Date.today (only one campaign will meet this criteria).</p>
  
  <p>Thanks!</p>