title: db4o - ignore specific class property
body: <p>Is there a way (meta property maybe) to tell db4o to simply ignore a specific property of a class?</p>
  
  <p>I can't see anywhere to do that.. </p>
  
  <p>For my purpose I have a bunch of data entity that i need to persist now and then. I also sometimes need to hold a ref to a UI element associated with it, but I don't want db4o to persist that element when I update the object.</p>
  
  <p>I can go around it by backing up, nulling the ref, saving, and finally restoring the reference but it seems really bad.</p>
  
  <p>Anyway I can tell db4o to ignore it altogether?</p>