title: Properties as indexed map in gae-datastore
body: <p>I have a little but important doubt about Low-Level Datastore from Google App Engine.
  I need a document structure like this :</p>
  
  <pre><code>{infNfe id="1234"
      det={nItem="1",prod="prodname"},
      det={nItem="2",prod="prodname"},
      det={nItem="3",prod="prodname"}
  }
  </code></pre>
  
  <p>Note that <strong>det</strong> element is a Map too, but unfortunately datastore do not accept Map as <em>indexed</em> property.</p>
  
  <p>Locking some example, I found something like it:</p>
  
  <pre><code>Entity i = new Entity("infNfe","key");
  i.setProperty("id",1234);
  Entity det1 = new Entity("det",i.getKey());
  det1.setProperty("nItem",1);
  det1.setProperty("prod","prodname");
  ..Others dests..
  </code></pre>
  
  <p>But, when I query some child entity, I get incomplete references.</p>
  
  <pre><code>Query dq= new Query("det");
  dq.setAncestor(i.getKey());
  ..Printing result..
  {nItem="1",prod="prodname"}
  </code></pre>
  
  <p>By this approach I can only get one <strong>det</strong> entity at a time.
  How can I get the parent and children at once ?</p>
  
  <p>Thanks.....</p>