a different object with the same identifier value was already associated with the session error on save

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Spring + Hibernate : a different object with the same identifier value was already associated with the session

I've been having problems with my hibernate annotations. I have a bidirectional relationship between 2 classes. Here's the mapping(thanks to axtavt):

@Entity 
public class Receipt implements Serializable { 
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "receipt")
    private List<Collection> collections; 
    ...
}      

@Entity 
public class Collection implements Serializable { 
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    @ManyToOne 
    @JoinColumn(name="ReceiptId") 
    private Receipt receipt; 
    ...
}

But when i try to save my receipt with a list of collections using:

Receipt r = new Receipt();
List<Collection> cols = new ArrayList<Collection>();
cols.add(new Collection());
r.setCollections(cols);
getHibernateTemplate().save(r);

It generates this error:

org.springframework.orm.hibernate3.HibernateSystemException: a different object with the same identifier value was already associated with the session: [com.coa.acctreports.pojo.Collection#0]; nested exception is org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.coa.acctreports.pojo.Collection#0]
 at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:679)
 at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412)
 at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:411)
 at org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374)
 at org.springframework.orm.hibernate3.HibernateTemplate.save(HibernateTemplate.java:683)
 at com.coa.acctreports.daoImp.AccountingReportsImpl.save(AccountingReportsImpl.java:35)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

but when i change it to

session.merge(receipt)

it has no errors but when i check my database the receiptId fk on the colllections table is set to null... Any help is appreciated. Thanks ^_^...

Answer 1

The mappedby annotation on the Receipt means that the Collection is actually the owning side of the relationship, which is clearly not what you intended since you have a cascade on the Receipt.

You should remove the mappedby on the Receipt and follow this example from the hibernate documentation:

@Entity 
public class Receipt implements Serializable { 
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;
    @OneToMany(cascade = CascadeType.ALL)
    @JoinColumn(name="ReceiptId")
    private List<Collection> collections; 
    ...
}      

@Entity 
public class Collection implements Serializable { 
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Long id;

    @ManyToOne 
    @JoinColumn(name="ReceiptId",insertable=false,updatable=false) 
    private Receipt receipt; 
    ...
}

Using the same code you have above to perform the save should work.

There is some more information on this here: http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/