class Topic

  has n, :article_topics
  has n, :articles, :through => :article_topics

  def associated_articles association_type
    Article.all :conditions => ["(`article_topics`.`association_type` = ?)", association_type]

    # I want to do this
    Article.all 'article_topics.association_type' => association_type
    # But DM complains that 'article_topics.association_type' is not a property
    # Design? or Bug?
  end
end