title: Rails find getting ActiveRecord::RecordNotFound
body: <p>I have a table that includes a "belongs to" in the model.
  The table includes the xx_id field to link the two tables.</p>
  
  <p>But, sometimes the xx_id is going to be blank.
  When it is, I get ActiveRecord::RecordNotFound.
  I don't want an error - I just want a blank display for this field.</p>
  
  <p>What do you suggest?</p>