title: Persistence functionality for ActiveModel
body: <p>I have a class <code>Document</code> that inherits from another class <code>MyGem::Record</code>. I am "mixing in" <code>ActiveModel</code> functionality so that instances look like <code>ActiveRecord</code> objects. I am not inheriting from <code>ActiveRecord::Base</code> because I am already inheriting from another class.</p>
  
  <p>I was wondering if I could somehow include some database persistence functionality for my <code>ActiveModel</code> flavored class. I could define my own <code>save</code> and <code>update</code> methods, but I would prefer not to.</p>
  
  <p>Alternatively, would it be possible do something like <code>include ActiveRecord</code> to get this functionality in my class?</p>
  
  <p>I know that DataMapper could handle this for me, but I would like to use the <code>ActiveRecord</code> model here if possible.</p>