I don't know if this is it but your problem could be that you are using
setters to set first and last name which is the way you are supposed to do
it (so that the enhancer can find all places where properties may be
modified) but you are directly setting the student property instead of using
a setter method and therefore the code may not be able to determine that the
student field has been dirtied. Try using a setter method for student
instead.
Stephen
www.cortexconnect.com
On Mon, Aug 29, 2011 at 6:35 AM, Bat wrote:
> I've 2 simple classes :
>
> public class Student {
> @PrimaryKey
> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
> com.google.appengine.api.datastore.Key key;
> @Persistent
> public String firstName;
> @Persistent
> public String lastName;
> }
> And
>
> public class Teacher {
>@PrimaryKey
> @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
>com.google.appengine.api.datastore.Key key;
>@Persistent
>public String firstName;
>@Persistent
>public String lastName;
>@Persistent
>public com.google.appengine.api.datastore.Key student;
> }
>
> First, I create a Teacher with only the fields 'firstname' &
> 'lastname' filled. It works. Then, I update my teacher with this
> code :
>
> Transaction tx = pm.currentTransaction();
> tx.begin();
> Teacher a = pm.getObjectById(Teacher.class,
> KeyFactory.stringToKey( the_key));
> if(a != null) {
> try {
> a.setFirstName("test");
> a.setLastName("test");
> a.student = KeyFactory.stringToKey( req.getParameter("student101-
> key"));
> tx.commit();
> }
> }
> pm.close();
> }
> }
> After this transaction, the fields "firstname" & "lastname" are
> correctly updated. However, the field "student" is still null. Do you
> know Why?
>
> Thank you very much
>
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