Does anyone have an example implementation of Ray Cromwell's article
on "Making JDO/JPA enhanced classes work over GWT RPC"? (http://
timepedia.blogspot.com/2009/04/google-appengine-and-gwt-now-
marriage.html)
I am unable to get the second part of his code into my IDE without
errors and am unsure how to implement it:
public <T> T mergeTransient(T tInstance) {
EntityManager e = em.get();
if(e.contains(tInstance)) {
e.persist(tInstance);
return tInstance;
} else {
Object primaryKey = PersistenceHelper.findPrimaryKey(tInstance);
if(primaryKey != null) {
Object entity = e.find(tInstance.getClass(), primaryKey);
if(entity == null) {
e.persist(tInstance);
return tInstance;
}
else {
try {
PersistenceHelper.copyPersistentFields(entity, tInstance);
} catch (IllegalAccessException e1) {
e1.printStackTrace();
throw new IllegalArgumentException("Can't copy fields from
transient class to persistent class.");
} catch (NoSuchMethodException e1) {
throw new IllegalArgumentException("Can't copy fields from
transient class to persistent class.");
} catch (InvocationTargetException e1) {
throw new IllegalArgumentException("Can't copy fields from
transient class to persistent class.");
}
e.persist(entity);
return (T) entity;
}
} else {
// primary key may be null, assume insert
e.persist(tInstance);
return tInstance;
}
}
}
If anyone has been able to successfully use this workaround and is
will to share example code I would appreciate it!
Thanks,
Mike
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