title: how to receive objects by condition in connecting table
body: <p>I have table <code>Games</code> and <code>Badges</code> they are connecting by table <code>BadgesGames</code>. </p>
  
  <pre><code>t.integer "badge_id"
  t.integer "game_id"
  t.boolean "shown",    default: false
  </code></pre>
  
  <p>I have <code>Game</code> object and i want find all <code>Badges</code> which wans't <code>shown</code></p>
  
  <pre><code>game_object.(condition?).badges
  </code></pre>
  
  <p>How to get it?</p>