title: How to query the datastore to get child objects and compare their properties using Java?
body: <p>I am implementing a project on the google app engine. I would like to query the datastore to refer to the child object's property and use it to identify the parent object.</p>
  
  <p>Think of these as the parent and child classes I am talking about:</p>
  
  <pre><code>class Parent {  
  String name;  
  Child child;  
  }      
  
  class Child{  
  String id;  
  }
  </code></pre>
  
  <p>I need to create a query on the <code>Parent</code> objects such that it takes the <code>id</code> property from the <code>Child</code> (which is in <code>Parent</code>) and use it to identify the <code>Parent</code> object I need.
  I know how bad the design is, but please tell me a way to do this. I would love to use the App Engine Datastore queries, but if not possible I'm open to the Java JDO queries too.</p>