title: How to use becomes in Rails
body: <p>I have a <code>Post</code> Class and a <code>Comment</code> Class. I have a post object and want to convert it to a Comment object. I went through Rails api and found becomes(klass).For now there is not association between a Post and Comment. So i tried </p>
  
  <pre><code>@post.becomes(Comment)
  </code></pre>
  
  <p>but becomes method could not be found for <code>@post</code> object. Am i missing something ?</p>