Hibernate failed to lazily initialize a collection of role no session or session was closed

Question

My code        Test public void testAddRoleAndAddUser          Role r   roleDao findByProperty  name    admin        if r    null            r   new Role            r setName  admin            r setDescription  Just administrator             roleDao save r              User u   dao get 1l       Set lt Role gt  roles   u getRoleSet        logger debug  Roles is null       roles    null        roles add r       dao save u          13 39 41 041 ERROR    org hibernate LazyInitializationException     failed to lazily initialize a   collection of role    xxx entity core User roleSet  no   session or session was closed   org hibernate LazyInitializationException    failed to lazily initialize a   collection of role    xxx entity core User roleSet  no   session or session was closed     at   org hibernate collection AbstractPersistentCollection throwLazyInitializationException AbstractPersistentCollection java 380      at   org hibernate collection AbstractPersistentCollection throwLazyInitializationExceptionIfNotConnected AbstractPersistentCollection java 372      at   org hibernate collection AbstractPersistentCollection initialize AbstractPersistentCollection java 365      at   org hibernate collection PersistentSet add PersistentSet java 212      at   sg com junglemedia test dao impl hibernate UserDaoTest testAddRoleAndAddUser UserDaoTest java 40      at   sun reflect NativeMethodAccessorImpl invoke0 Native   Method    at   sun reflect NativeMethodAccessorImpl invoke NativeMethodAccessorImpl java 39      at   sun reflect DelegatingMethodAccessorImpl invoke DelegatingMethodAccessorImpl java 25      at   java lang reflect Method invoke Method java 597      at   org junit runners model FrameworkMethod 1 runReflectiveCall FrameworkMethod java 44      at   org junit internal runners model ReflectiveCallable run ReflectiveCallable java 15      at   org junit runners model FrameworkMethod invokeExplosively FrameworkMethod java 41      at   org junit internal runners statements InvokeMethod evaluate InvokeMethod java 20      at   org junit internal runners statements RunBefores evaluate RunBefores java 28      at   org junit runners BlockJUnit4ClassRunner runChild BlockJUnit4ClassRunner java 76      at   org junit runners BlockJUnit4ClassRunner runChild BlockJUnit4ClassRunner java 50      at   org junit runners ParentRunner 3 run ParentRunner java 193      at   org junit runners ParentRunner 1 schedule ParentRunner java 52      at   org junit runners ParentRunner runChildren ParentRunner java 191      at   org junit runners ParentRunner access 000 ParentRunner java 42      at   org junit runners ParentRunner 2 evaluate ParentRunner java 184      at   org junit runners ParentRunner run ParentRunner java 236      at   org eclipse jdt internal junit4 runner JUnit4TestReference run JUnit4TestReference java 46      at   org eclipse jdt internal junit runner TestExecution run TestExecution java 38      at   org eclipse jdt internal junit runner RemoteTestRunner runTests RemoteTestRunner java 467      at   org eclipse jdt internal junit runner RemoteTestRunner runTests RemoteTestRunner java 683      at   org eclipse jdt internal junit runner RemoteTestRunner run RemoteTestRunner java 390      at   org eclipse jdt internal junit runner RemoteTestRunner main RemoteTestRunner java 197    Anyone help

User · Answer

Your trying to load the lazy loaded collection  but the hibernate session is closed or unavailable  the best solution for this problem  change the lazy loaded object to eager fetch   FetchType EAGER loading  this problem will solve

User · Answer

You re most likely closing the session inside of the RoleDao  If you close the session then try to access a field on an object that was lazy-loaded  you will get this exception  You should probably open and close the session transaction in your test

User · Answer

The following code can cause similar error     using  var session   SessionFactory OpenSession      using  var tx   session BeginTransaction              movie   session Get lt Movie gt  movieId         tx Commit          Assert That movie Actors Count    1     You can fix it simply     using  var session   SessionFactory OpenSession      using  var tx   session BeginTransaction              movie   session Get lt Movie gt  movieId         Assert That movie Actors Count    1         tx Commit

User · Answer

In your entity class  when you declare mapping from user to roles  try specifying the fetchType to EAGER  Some thing like this     OneToMany fetch FetchType EAGER  public Collection lt Role gt  getRoleSet             UPDATE   Recent comments this answer s received make me revisit this  It s been a while since I answered  when I only started working with Hibernate  What Rafael and Mukus say are reasonable  If you have a large collection  you shouldn t use eager fetching  It jointly selects all data mapped to your entry and loads to memory  An alternative to this is to still use lazy fetching and open a Hibernate session each time you need to work on the related collection  i e  each time you need to invoke getRoleSet method  This way  Hibernate will execute the select query to database each time this method is invoked and doesn t keep the collection data in memory  You can refer to my post here for details  http   khuevu github io 2013 01 20 understand-hibernate html  That s said  it can depend on your actual use case  If your collection data is small and you frequently need to query the data  you will better off using eager fetching  I think  in your specific case  a collection of role is probably quite small and suitable to use eager fetching

User · Answer

for me it worked the approach that I used in eclipselink as well  Just call the size   of the collection that should be loaded before using it as parameter to pages   for  Entity e   entityListKeeper getEntityList          e getListLazyLoadedEntity   size        Here entityListKeeper has List of Entity that has list of LazyLoadedEntity  If you have just therelation Entity has list of LazyLoadedEntity then the solution is   getListLazyLoadedEntity   size

User · Answer

You can try to add  Transactional annotation to your bean or method  if declaration of all variables places in method

User · Answer

You have different choices to handle this  It seem like its taking us back to old good plain SQL days     Read this  http   www javacodegeeks com 2012 07 four-solutions-to-lazyinitializationexc 05 html

User · Answer

In my case the Exception occurred because I had removed the  hibernate enable lazy load no trans true  in the  hibernate properties  file     I had made a copy and paste typo

User · Answer

I was experiencing the same issue so just added the  Transactional annotation from where I was calling the DAO method  It just works  I think the problem was Hibernate doesn t allow to retrieve sub-objects from the database unless specifically all the required objects at the time of calling

User · Answer

I ve had this issue especially when entities are mashalled by Jaxb   Jax-rs   I ve used the pre-fetch strategy  but I have also found it effective to provide two entities     Full-blown entity with all collections mapped as EAGER Simplified entity with most or all collections trimmed out   Common fields and be mapped in  MappedSuperclass and extended by both entity implementations   Certainly if you always need the collections loaded  then there is no reason to not to EAGER load them   In my case I wanted a stripped down version of the entity to display in a grid

[java] Hibernate: failed to lazily initialize a collection of role, no session or session was closed

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