Getting org.hibernate.NonUniqueObjectException within my transaction

Question

I'm getting org.hibernate.NonUniqueObjectException while performing these steps.

session.beginTransaction();
TransactionEntry te = (TransactionEntry)session.get(TransactionEntry.class, primaryKey);
session.getTransaction().commit();
.
.
.
session.beginTransaction();
session.saveOrUpdate(te.getAccount());
session.delete(te);
session.delete(te.getTransaction());
session.getTransaction().commit();

Snapshot of my model is as follows:

TransactionEntry class

@Entity
public class TransactionEntry {
    @Id
    @GeneratedValue
    private long txnEntryId;

    @ManyToOne
    @JoinColumn(name = "account")
    private Account account;

    @ManyToOne
    @JoinColumn(name = "txnId")
    private TransactionTable transaction;
}

Account Class

@Entity
public class Account {
    @Id
    @GeneratedValue
    private long accountId;
}

TransactionTable class

@Entity
public class TransactionTable {
    @Id
    @GeneratedValue
    private long txnId;

    @OneToMany(targetEntity = TransactionEntry.class, fetch = FetchType.LAZY,
            mappedBy = "transaction", cascade = CascadeType.ALL)
    private List<TransactionEntry> transactionEntries;
}

I'm getting the following exception:

org.hibernate.NonUniqueObjectException: a different object with the same
identifier value was already associated with the
session: [com.pratikabu.pem.model.Account#1]

If I remove the session.delete(te.getTransaction()); statement then the code is working fine or else it is throwing the above exception. Is there something I'm missing.

Answer 1

Here is what's happening step by step:

• line session.saveOrUpdate(te.getAccount()); attach the Account object ( with id 1 ) to the session
• in the line session.delete(te.getTransaction()); , before deleting, hibernate tries to load the collection of TransactionEntry objects (because of the cascade, the objects in the collection need to be deleted too).
• but while loading the TransactionEntry objects from the collection, hibernate will load the member Account object too because it's mapped with a @ManyToOne annotation that has an EAGER default fetch.
• when reaching the TransactionEntry object that corresponds to the Account with id 1 hibernate throws the above exception because that Account already exists in the session.

Answer 2

session.delete(te) - 它将删除TransactionEntry以及TransactionTable因为cascade = CascadeType.ALL所以session.delete(te.getTransaction()) with this line you wont have any thing这就是为什么它说NonUniqueObjectException