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

possible duplicate:
spring + hibernate : different object same identifier value associated session

i've been having problems hibernate annotations. have bidirectional relationship between 2 classes. here's mapping(thanks 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 try save receipt 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 error:

org.springframework.orm.hibernate3.hibernatesystemexception: different object same identifier value associated session: [com.coa.acctreports.pojo.collection#0]; nested exception org.hibernate.nonuniqueobjectexception: different object same identifier value associated session: [com.coa.acctreports.pojo.collection#0]  @ org.springframework.orm.hibernate3.sessionfactoryutils.converthibernateaccessexception(sessionfactoryutils.java:679)  @ org.springframework.orm.hibernate3.hibernateaccessor.converthibernateaccessexception(hibernateaccessor.java:412)  @ org.springframework.orm.hibernate3.hibernatetemplate.doexecute(hibernatetemplate.java:411)  @ org.springframework.orm.hibernate3.hibernatetemplate.executewithnativesession(hibernatetemplate.java:374)  @ org.springframework.orm.hibernate3.hibernatetemplate.save(hibernatetemplate.java:683)  @ com.coa.acctreports.daoimp.accountingreportsimpl.save(accountingreportsimpl.java:35)  @ sun.reflect.nativemethodaccessorimpl.invoke0(native method)  @ sun.reflect.nativemethodaccessorimpl.invoke(nativemethodaccessorimpl.java:39)  @ sun.reflect.delegatingmethodaccessorimpl.invoke(delegatingmethodaccessorimpl.java:25) 

but when change

session.merge(receipt) 

it has no errors when check database receiptid fk on colllections table set null... appreciated. ^_^...

the mappedby annotation on receipt means collection owning side of relationship, not intended since have cascade on receipt.

you should remove mappedby on receipt , follow example 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,updateable=false)      private receipt receipt;      ... } 

using same code have above perform save should work.

there more information on here: http://docs.jboss.org/hibernate/annotations/3.5/reference/en/html_single/