contradicting constraints and statements issue order

[ebu]

Hi.
I need to make statements to be issued to the database in an original order (delete, insert as they appears in code) rather then as hibernate default insert first then delete.
In a bit more details, i have two entities A and B, such that
A.java

@Entity(access=AccessType.FIELD)
public class A implements Serializable{
...
 @OneToMany(mappedBy = "a", cascade = CascadeType.ALL)
 private Collection<B> bs;
...

 @PrePersist
 @PreUpdate
 public void validate(){
 if (bs == null || bs.size() == 0) {
 throw new RuntimeException("xxx");
 }
 }
.....

B.java

@Table(
 uniqueConstraints={@UniqueConstraint(columnNames={"name", "a_id"})}
)
public class B implements Serializable{
...
 B(String name, A a) {
 this.name = name;
 this.a = a;
 }

 @Id(generate = GeneratorType.AUTO)
 private int id;

 private String name;

 @ManyToOne
 private A a;
}

besides this i need to validate A in preUpdate/Persist that there is at least one element in bs collection. Finally i need to execute following code:

 A a = new A();
 B b1 = new B(a, "x");
 a.addB(b1);
 manager.persist(a);
 a.removeB(b1);
 manager.remove(b1);
 a.addB(new B(a, "x"));

 manager.flush();

but it gives me Violation of UNIQUE KEY constraint since it tries to insert firts, then delete. On the other hand if i try to flush after remove i got validator exception if A also was modified in a some way.
Any suggestions? It would be greate if validation could be palced in a callback method to be called on commit.

wbr, eugen.

[sethladd]

Hi,

Did you ever find a solution to this? We need our delete statements to be flushed before our insert statements (in other words, in the order that we execute the methods that result in the statements), and we really don't want to put Session calls inside our domain objects.

Thanks!
Seth

[gavin.king]

Manually call flush() in between the call to remove() and the call to persist().

[ebu]

Hi.

Unfortunately i come up with calling flush as suggested by gavin. Thus this forces me either to call entity manager from an entity bean or move domain logic into the service. I've chosen the first.

wbr, eugen.

[sethladd]

Thanks. We really want to avoid putting any calls to the EntityManager inside our domain objects. For the time being, we've split up the deletes and adds into two different methods, and called them from the service bean. deleteThem(), flush(), addThem(). Ugly, but it works.

After thinking about it, we could enable immediate flushing for this service method only.