Hibernate Error a different object with the same identifier value was already associated with the session

Question

I essentially have some objects in this configuration  the real data model is a bit more complex     A has a many-to-many relationship with B   B has inverse  true   B has a many-to-one relationship with C   I have cascade set to  save-update   C is a kind of type category table    Also  I should probably mention that the primary keys are generated by the database on save   With my data  I sometimes run into problems where A has a set of different B objects  and these B objects refer to the same C object   When I call session saveOrUpdate myAObject   I get a hibernate error saying   a different object with the same identifier value was already associated with the session  C   I know that hibernate can t insert update delete the same object twice in the same session  but is there some way around this  This doesn t seem like it would be that uncommon of a situation   During my research of this problem  I have seen folks suggest the use of session merge    but when I do that  any  conflicting  objects get inserted into the database as blank objects with all values set to null  Clearly that isn t what we want    Edit  Another thing I forgot to mention is that  for architectural reasons beyond my control   each read or write needs to be done in a separate session

User · Answer

Another case when same error message can by generated, custom allocationSize:

@Id
@Column(name = "idpar")
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "paramsSequence")
@SequenceGenerator(name = "paramsSequence", sequenceName = "par_idpar_seq", allocationSize = 20)
private Long id;

without matching

alter sequence par_idpar_seq increment 20;

can cause constraint validation during insert(that one is easy to understand) or ths "a different object with the same identifier value was already associated with the session" - this case was less obvious.

User · Answer

you might not be setting the identifier of the object before calling update query

User · Answer

If left an expressions tab in my IDE open which was making a hibernate get call on the object causing this exception  I was trying to delete this same object  Also I had a breakpoint on the delete call which seems to be necessary to get this error to happen  Simply making another expressions tab to be the front tab or changing the setting so that the ide does not stop on breakpoints solved this problem

User · Answer

Just came across this message but in c  code  Not sure if it s relevant  exactly the same error message though    I was debugging the code with breakpoints and expanded some collections through private members while debugger was at a breakpoint  Having re-run the code without digging through structures made the error message go away  It seems like the act of looking into private lazy-loaded collections has made NHibernate load things that were not supposed to be loaded at that time  because they were in private members    The code itself is wrapped in a fairly complicated transaction that can update large number of records and many dependencies as part of that transaction  import process    Hopefully a clue to anyone else who comes across the issue

User · Answer

You only need to do one thing  Run session object clear   and then save the new object  This will clear the session  as aptly named  and remove the offending duplicate object from your session

User · Answer

I had this error few days a go and I sped too many time on fixing this error     public boolean save OrderHeader header        Session session   sessionFactory openSession          Transaction transaction   session beginTransaction         try           session save header            for  OrderDetail detail   header getDetails                  session save detail                      transaction commit            session close             return true        catch  HibernateException exception             exception printStackTrace            transaction rollback            return false            Before i get this error   I didn t have mentioned ID generation type on the OrderDetil Object  when without generating Orderdetails  id it keeps Id as 0 for every OrderDetail objects   this what  jbx explained  Yes it is the best answer  this one example how it happens

User · Answer

Transfer the task of assigning the object ID from Hibernate to the database by using    lt generator class  native   gt    This solved the problem for me

User · Answer

This means you are trying to save multiple rows in your table with the reference to the same object   check your Entity Class  id property    Id private Integer id    to   Id  GeneratedValue strategy   GenerationType IDENTITY   Column unique   true  nullable   false  private Integer id

User · Answer

In addition to all the previous answers  a possible fix to this problem in a large scale project  if your using a Value Object for your classes don t set the id attribute in the VO Transformer class

User · Answer

just commit current transaction    currentSession getTransaction   commit       now you can begin another Transaction and do anything on entity

User · Answer

I met the problem because of the primary key generation is wrong when I insert a row like this   public void addTerminal String typeOfDevice Map lt Byte Integer gt  map               TODO Auto-generated method stub         try               Set lt Byte gt  keySet   map keySet                for  Byte byte1   keySet                    Device device new Device                    device setNumDevice DeviceCount map get byte1                    device setTimestamp System currentTimeMillis                     device setTypeDevice byte1                   this getHibernateTemplate   save device                             System out println  hah             catch  Exception e                   TODO  handle exception             logger warn  wrong                logger warn e getStackTrace   e getMessage                   I change the id generator class to identity   lt id name  id  type  int  gt       lt column name  id    gt       lt generator class  identity     gt    lt  id gt

User · Answer

One way to solve the above problem will be to override the hashcode    Also flush the hibernate session before and after save     getHibernateTemplate   flush      Explicitly setting the detached object to null also helps

User · Answer

Most probably its because the B objects are not referring to the same Java C object instance  They are referring to the same row in the database  i e  the same primary key  but they re different copies of it    So what is happening is that the Hibernate session  which is managing the entities would be keeping track of which Java object corresponds to the row with the same primary key   One option would be to make sure that the Entities of objects B that refer to the same row are actually referring to the same object instance of C  Alternatively turn off cascading for that member variable  This way when B is persisted C is not  You will have to save C manually separately though  If C is a type category table  then it probably makes sense to be that way

User · Answer

Just set cascade to MERGE  that should do the trick

User · Answer

Find the  Cascade  atribute in Hibernate and delete it  When you set  Cascade  available  it will call other operations  save  update and delete  on another entities which has relationship with related classes  So same identities value will be  happened   It worked with me

User · Answer

In my case only flush   did not work  I had to use a clear   after flush     public Object merge final Object detachedInstance                this getHibernateTemplate   flush            this getHibernateTemplate   clear            try                       this getHibernateTemplate   evict detachedInstance

User · Answer

if you use EntityRepository then use saveAndFlush instead of save

User · Answer

Add the annotation  GeneratedValue to the bean you are inserting

User · Answer

Try to place the code of your query before  That fix my problem  e g  change this   query1  query2 - get the error  update   to this   query2 query1 update

User · Answer

I agree with  Hemant Kumar  thank you very much  According his solution  I solved my problem   For example    Test public void testSavePerson         try  Session session   sessionFactory openSession              Transaction tx   session beginTransaction            Person person1   new Person            Person person2   new Person            person1 setName  222            person2 setName  111            session save person1           session save person2           tx commit              Person java  public class Person       private int id      private String name        Id      Column name    id       public int getId             return id             public void setId int id            this id   id              Basic      Column name    name       public String getName             return name             public void setName String name            this name   name             This code always make mistake in my application  A different object with the same identifier value was already associated with the session  later I found out that I forgot to autoincrease my primary key    My solution is to add this code on your primary key    GeneratedValue strategy   GenerationType AUTO

User · Answer

Make Sure  your entity have same Generation Type with all Mapped Entitys  Ex   UserRole   public class UserRole extends AbstractDomain     Id  GeneratedValue strategy   GenerationType AUTO  private Long id   private String longName   private String shortName    Enumerated EnumType STRING  private CommonStatus status   private String roleCode   private Long level    Column columnDefinition    integer default 0   private Integer subRoleCount   private String modification    ManyToOne fetch   FetchType LAZY  private TypeOfUsers licenseType       Module     public class Modules implements Serializable     Id  GeneratedValue strategy   GenerationType AUTO  private Long id   private String longName   private String shortName       Main Entity with Mapping  public class RoleModules implements Serializable    Id  GeneratedValue strategy   GenerationType AUTO  private Long id    ManyToOne fetch   FetchType LAZY  cascade   CascadeType MERGE  private UserRole role    ManyToOne fetch   FetchType LAZY  cascade   CascadeType MERGE  private Modules modules    Type type    yes no   private boolean isPrimaryModule   public boolean getIsPrimaryModule         return isPrimaryModule

[java] Hibernate Error: a different object with the same identifier value was already associated with the session

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