for instance, you can just use a Key and reference the Person in the Telephone.
>>>>>you are right. and i just do it as you say. public class Telephone{ @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String telephone_id; @Persistent private String person_id; //this field point to Person } my question is " if person have telephone( telephone1,telephone2,telephone3) and user update person's telephone is telephone2,telephone3,telephone4, how to implements this? " but in a same transactions , I need update 2 telephone object .----------telephone1.person_id=null telephone4.person_id=person_id. and the 2 telephone object is not in same entity group. the question seem to equal " how to update multi object (same class) in same transaction?" Thank you for your help -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.