title: Eager loading a named_scope from an association in Rails
body: <p>Is there any way to eager load a named_scope from an association?</p>
  
  <p>I have my Article model:</p>
  
  <pre><code>class Article &lt; ActiveRecord::Base
    has_many :comments
  end
  </code></pre>
  
  <p>and my Comment model:</p>
  
  <pre><code>class Comment &lt; ActiveRecord::Base
    belongs_to :article
  
    named_scope :approved, :conditions =&gt; { :approved =&gt; true }
    named_scope :unapproved, :conditions =&gt; { :approved =&gt; false }
  end
  </code></pre>
  
  <p>I could eager load all comments for an article with:</p>
  
  <pre><code>@article = Article.find(params[:id], :include =&gt; :comments)
  </code></pre>
  
  <p>How can I do the same, but only for approved comments?</p>