I have
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
public Linf getLinf() {
return linf;
}
and
@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL, targetEntity = MessageEntry.class)
public Set<MessageEntry> getMessageEntries() {
return messageEntries;
}
I need to remove single messageEntry from database. If I say sess.delete(messageEntry), then I get index exception since its in Linf.messageEntries collection. Stateless session can't load collection, so I have to load elements of Linf.messageEntries mannually and then remove one of them:
List linfs = sess.createQuery(
"SELECT l FROM Linf l " +
"JOIN l.messageEntries e WHERE e=:e")
.setParameter("e", messageEntry).list();
if (linfs.size()>1) throw new RuntimeException();
Linf linf = (Linf) linfs.get(0);
List<MessageEntry> curEntries =
sess.createQuery(
"SELECT e FROM Linf l " +
"JOIN l.messageEntries e WHERE l=:l")
.setParameter("l", linf).list();
for (int i = 0; i < curEntries.size(); i++) {
if (curEntries.get(i).getId().equals(messageEntry.getId())) {
curEntries.remove(i);
break;
}
}
Set<MessageEntry> cur = new HashSet<MessageEntry>();
cur.addAll(curEntries);
linf.setMessageEntries(cur);
messageEntry.setLinf(null);
sess.update(messageEntry);
sess.update(linf);
sess.delete(messageEntry);
I get ConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails ( db
. linf_messageentry
, CONSTRAINT FK5039A8B5E770809A
FOREIGN KEY ( messageEntries_id
) REFERENCES messageentry
( id
)). How can I perform this task? Thank you.
Your mapping is wrong. Instead of having a bidirectional one-to-many association, using a foreign key in MessageEntry, you have a OneToMany association using a join table ( linf_messageentry
), and another, distinct, ManyToOne association using a foreign key.
The one side must be marked as the inverse of the many side, using the mappedBy
attribute:
// This is the owner side of the association, because it doesn't have
// the mappedBy attribute.
// it uses a join column by default
@ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
public Linf getLinf() {
return linf;
}
and
// This is the inverse side, because it has the mappedBy attribute
// since it's mappedBy linf, hibernate uses the same mapping as the one
// described on the linf property: a join column
@OneToMany(mappedBy = "linf", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
public Set<MessageEntry> getMessageEntries() {
return messageEntries;
}
Also, note that:
targetEntity
attribute is completly redundant: Hibernate knows the target entity from the type of the collection: Set<MessageEntry>
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