title: Grails trouble saving object id
body: <p>id is present in the params but does not save to the db. for example </p>
  
  <pre><code>[book.id:1, comments: good]
  </code></pre>
  
  <p>comments will save to db but book.id does not. </p>
  
  <p>I need to figure out how to save params.book.id into the db column BOOK_ID that was created from the hasmany/belongsTo relationship. </p>