Hi Fred, Thanks for your response. This is what I suspected too that the entity groups might not be able to change. This actually brings me to the conclusion that we might not want to keep any owned entities at all. We are in the process of converting a legacy application to GAE and in the process we have been breaking out relationships due to multiple problems. I would write about all the problems that we faced and the workarounds and link it here. This relationship was probably one of the last bastions that we had remaining. With what you mentioned this might have to be broken too since a user can move around departments as a valid business case.
So let me ask the community this question, does anyone see the benefit of maintaining relations at all? using JPA/JDO. From the complex queries that a normal web app would have you would fall into situations where you would need to use more and more of unowned relationships. Is that true? or am I missing something. Regards | Vikas www.inphina.com www.thoughts.inphina.com On Aug 3, 10:00 pm, Frederik Pfisterer <[email protected]> wrote: > You have to use unowned relationships and not place the department and > the user in the same entity group. > See:http://code.google.com/intl/de-DE/appengine/docs/java/datastore/relat... > use for UserDepartment: > private Set<Key> users = new HashSet<Key>(); > and for User: > private Key userDepartmentKey; > > Entity groups cannot be changed once being established. > If you want the relationships like you have them, you would have to > change the Key of the User object (it's identity) to place it in the > entity group of another department, since the department's (parent) > key is part of the user key like in a path. > > Cheers, > Fred > > On 3 Aug., 15:09, Vikas Hazrati <[email protected]> wrote: > > > > > Oops I somehow managed to hit the submit without the full question... > > Apologies...Let me start again > > > I have 2 entities UserDepartment and User, which are defined as > > follows > > @Entity > > public class UserDepartment extends DomainObject<Long, > > UserDepartment> > > { > > @Id > > @GeneratedValue(strategy = GenerationType.IDENTITY) > > private Long departmentId; > > @OneToMany(mappedBy = "userDepartment", cascade = > > CascadeType.ALL, fetch=FetchType.EAGER) > > private Set<User> users = new HashSet<User>(); > > > and > > > @Entity > > public class User extends DomainObject<Long, User> { > > @Id > > @GeneratedValue(strategy = GenerationType.IDENTITY) > > @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", > > value = "true") > > private String encodedKey; > > @Extension(vendorName = "datanucleus", key = "gae.pk-id", > > value = "true") > > private Long userId; > > private String username; > > @ManyToOne(fetch = FetchType.EAGER) > > private UserDepartment userDepartment; > > > As you would notice that UserDepartment is the parent of the User. Now > > once I persist the entity group, i want to modify the user so that it > > belongs to a different department now. > > > What is the best way to do that? > > > If i remove the UserDepartment from the User and then assign a new > > UserDepartment to it then I get into the issue of trying to access > > multiple entity groups in the same transaction. > > > Regards | Vikaswww.inphina.com > > > On Aug 3, 6:05 pm, Vikas Hazrati <[email protected]> wrote: > > > > I have 2 entities UserDepartment and User, which are defined as > > > follows > > > > @Entity > > > public class UserDepartment extends DomainObject<Long, UserDepartment> > > > { > > > > @Id > > > @GeneratedValue(strategy = GenerationType.IDENTITY) > > > private Long departmentId; > > > > and > > > > @Entity > > > public class User extends DomainObject<Long, User> { > > > > @Id > > > @GeneratedValue(strategy = GenerationType.IDENTITY) > > > @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", > > > value > > > = "true") > > > private String encodedKey; > > > > @Extension(vendorName = "datanucleus", key = "gae.pk-id", value = > > > "true") > > > private Long userId; > > > > private String username; > > > @ManyToOne(fetch = FetchType.EAGER) > > > private UserDepartment userDepartment; -- 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 [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.
