How to convert a Hibernate proxy to a real entity object

Question

During a Hibernate Session  I am loading some objects and some of them are loaded as proxies due to lazy loading  It s all OK and I don t want to turn lazy loading off   But later I need to send some of the objects  actually one object  to the GWT client via RPC  And it happens that this concrete object is a proxy  So I need to turn it into a real object  I can t find a method like  materialize  in Hibernate   How can I turn some of the objects from proxies to reals knowing their class and ID   At the moment the only solution I see is to evict that object from Hibernate s cache and reload it  but it is really bad for many reasons

User · Answer

The way I recommend with JPA 2    Object unproxied    entityManager unwrap SessionImplementor class  getPersistenceContext   unproxy proxy

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Starting from Hiebrnate 5 2 10 you can use Hibernate proxy method to convert a proxy to your real entity   MyEntity myEntity    MyEntity  Hibernate unproxy  proxyMyEntity

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The another workaround is to call   Hibernate initialize extractedObject getSubojbectToUnproxy       Just before closing the session

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I ve written following code which cleans object from proxies  if they are not already initialized   public class PersistenceUtils        private static void cleanFromProxies Object value  List lt Object gt  handledObjects            if   value    null   amp  amp    isProxy value    amp  amp   containsTotallyEqual handledObjects  value                 handledObjects add value               if  value instanceof Iterable                    for  Object item    Iterable lt   gt   value                        cleanFromProxies item  handledObjects                                   else if  value getClass   isArray                      for  Object item    Object    value                        cleanFromProxies item  handledObjects                                               BeanInfo beanInfo   null              try                   beanInfo   Introspector getBeanInfo value getClass                   catch  IntrospectionException e                       LOGGER warn e getMessage    e                             if  beanInfo    null                    for  PropertyDescriptor property   beanInfo getPropertyDescriptors                          try                           if   property getWriteMethod      null   amp  amp   property getReadMethod      null                                 Object fieldValue   property getReadMethod   invoke value                               if  isProxy fieldValue                                     fieldValue   unproxyObject fieldValue                                   property getWriteMethod   invoke value  fieldValue                                                             cleanFromProxies fieldValue  handledObjects                                                   catch  Exception e                               LOGGER warn e getMessage    e                                                                              public static  lt T gt  T cleanFromProxies T value            T result   unproxyObject value           cleanFromProxies result  new ArrayList lt Object gt              return result             private static boolean containsTotallyEqual Collection lt   gt  collection  Object value            if  CollectionUtils isEmpty collection                 return false                    for  Object object   collection                if  object    value                    return true                                  return false             public static boolean isProxy Object value            if  value    null                return false                    if   value instanceof HibernateProxy      value instanceof PersistentCollection                 return true                    return false             private static Object unproxyHibernateProxy HibernateProxy hibernateProxy            Object result   hibernateProxy writeReplace            if    result instanceof SerializableProxy                 return result                    return null              SuppressWarnings  unchecked       private static  lt T gt  T unproxyObject T object            if  isProxy object                 if  object instanceof PersistentCollection                    PersistentCollection persistentCollection    PersistentCollection  object                  return  T  unproxyPersistentCollection persistentCollection                 else if  object instanceof HibernateProxy                    HibernateProxy hibernateProxy    HibernateProxy  object                  return  T  unproxyHibernateProxy hibernateProxy                 else                   return null                                  return object             private static Object unproxyPersistentCollection PersistentCollection persistentCollection            if  persistentCollection instanceof PersistentSet                return unproxyPersistentSet  Map lt      gt   persistentCollection getStoredSnapshot                       return persistentCollection getStoredSnapshot               private static  lt T gt  Set lt T gt  unproxyPersistentSet Map lt T    gt  persistenceSet            return new LinkedHashSet lt T gt  persistenceSet keySet                I use this function over result of my RPC services  via aspects  and it cleans recursively all result objects from proxies  if they are not initialized

User · Answer

Try to use Hibernate getClass obj

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I found a solution to deproxy a class using standard Java and JPA API  Tested with hibernate  but does not require hibernate as a dependency and should work with all JPA providers   Onle one requirement - its necessary to modify parent class  Address  and add a simple helper method   General idea  add helper method to parent class which returns itself  when method called on proxy  it will forward the call to real instance and return this real instance   Implementation is a little bit more complex  as hibernate recognizes that proxied class returns itself and still returns proxy instead of real instance  Workaround is to wrap returned instance into a simple wrapper class  which has different class type than the real instance   In code   class Address      public AddressWrapper getWrappedSelf            return new AddressWrapper this               class AddressWrapper       private Address wrappedAddress          To cast Address proxy to real subclass  use following   Address address   dao getSomeAddress       Address deproxiedAddress   address getWrappedSelf   getWrappedAddress    if  deproxiedAddress instanceof WorkAddress    WorkAddress workAddress    WorkAddress deproxiedAddress

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With Spring Data JPA and Hibernate  I was using subinterfaces of JpaRepository to look up objects belonging to a type hierarchy that was mapped using the  join  strategy   Unfortunately  the queries were returning proxies of the base type instead of instances of the expected concrete types   This prevented me from casting the results to the correct types   Like you  I came here looking for an effective way to get my entites unproxied   Vlad has the right idea for unproxying these results  Yannis provides a little more detail   Adding to their answers  here s the rest of what you might be looking for   The following code provides an easy way to unproxy your proxied entities   import org hibernate engine spi PersistenceContext  import org hibernate engine spi SessionImplementor  import org springframework beans factory annotation Autowired  import org springframework data jpa repository JpaContext  import org springframework stereotype Component    Component public final class JpaHibernateUtil        private static JpaContext jpaContext        Autowired     JpaHibernateUtil JpaContext jpaContext            JpaHibernateUtil jpaContext   jpaContext             public static  lt Type gt  Type unproxy Type proxied  Class lt Type gt  type            PersistenceContext persistenceContext               jpaContext              getEntityManagerByManagedType type               unwrap SessionImplementor class               getPersistenceContext            Type unproxied    Type  persistenceContext unproxyAndReassociate proxied           return unproxied             You can pass either unproxied entites or proxied entities to the unproxy method   If they are already unproxied  they ll simply be returned   Otherwise  they ll get unproxied and returned   Hope this helps

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Thank you for the suggested solutions  Unfortunately  none of them worked for my case  receiving a list of CLOB objects from Oracle database through JPA - Hibernate  using a native query   All of the proposed approaches gave me either a ClassCastException or just returned java Proxy object  which deeply inside contained the desired Clob    So my solution is the following  based on several above approaches    Query sqlQuery   manager createNativeQuery queryStr   List resultList   sqlQuery getResultList    for   Object resultProxy   resultList         String unproxiedClob   unproxyClob resultProxy       if   unproxiedClob    null            resultCollection add unproxiedClob            private String unproxyClob Object proxy        try           BeanInfo beanInfo   Introspector getBeanInfo proxy getClass             for  PropertyDescriptor property   beanInfo getPropertyDescriptors                  Method readMethod   property getReadMethod                if   readMethod getName   contains  getWrappedClob                       Object result   readMethod invoke proxy                   return clobToString  Clob  result                                     catch  InvocationTargetException   IntrospectionException   IllegalAccessException   SQLException   IOException e            LOG error  Unable to unproxy CLOB value    e             return null     private String clobToString Clob data  throws SQLException  IOException       StringBuilder sb   new StringBuilder        Reader reader   data getCharacterStream        BufferedReader br   new BufferedReader reader        String line      while  null     line   br readLine                sb append line             br close         return sb toString        Hope this will help somebody

User · Answer

Since Hibernate ORM 5 2 10  you can do it likee this  Object unproxiedEntity   Hibernate unproxy proxy    Before Hibernate 5 2 10  the simplest way to do that was to use the unproxy method offered by Hibernate internal PersistenceContext implementation  Object unproxiedEntity     SessionImplementor  session                            getPersistenceContext                             unproxy proxy

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Here s a method I m using       public static  lt T gt  T initializeAndUnproxy T entity        if  entity    null            throw new             NullPointerException  Entity passed for initialization is null               Hibernate initialize entity       if  entity instanceof HibernateProxy            entity    T    HibernateProxy  entity  getHibernateLazyInitializer                    getImplementation              return entity

[java] How to convert a Hibernate proxy to a real entity object

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