title: Choosing only certain children of models in Rails
body: <p>Say I have a model User which has_many Post children.</p>
  
  <p>Obviously I can access the children using something like this:</p>
  
  <pre><code>user = User.first
  posts = user.posts
  </code></pre>
  
  <p>but how can I pare down those posts to those that meet certain conditions?</p>
  
  <pre><code>user = User.first
  posts = user.posts
  recent_posts = posts.where(:created_at =&gt; &gt; (Time.now - 1.day))
  </code></pre>
  
  <p>I'm on Rails 2.3.11</p>