title: Locate customer by custom attribute in Magento
body: <p>I have a custom attribute called rms_id. It's a unique account number that's associated with our customers in another database. I need a way to lookup the customer by this id, without hitting the database manually.</p>
  
  <p>As of now, I can load the customer by email address like so:</p>
  
  <pre><code>$customer-&gt;loadByEmail($data['email']);
  </code></pre>
  
  <p>This is great, however the email is not always available. The RMS id is. Is there any way to load a user by the custom attribute? </p>
  
  <p>In theory, the following would work:</p>
  
  <pre><code>$customer-&gt;loadByRmsId($data['account_id']);
  </code></pre>
  
  <p>However it errors out. Any help would be much appreciated.</p>