How to fix org hibernate LazyInitializationException - could not initialize proxy - no Session

Question

I get the following exception   Exception in thread  main  org hibernate LazyInitializationException  could not initialize proxy - no Session     at org hibernate proxy AbstractLazyInitializer initialize AbstractLazyInitializer java 167      at org hibernate proxy AbstractLazyInitializer getImplementation AbstractLazyInitializer java 215      at org hibernate proxy pojo javassist JavassistLazyInitializer invoke JavassistLazyInitializer java 190      at sei persistence wf entities Element    jvstc68 47 getNote Element    jvstc68 47 java      at JSON to XML createBpmnRepresantation JSON to XML java 139      at JSON to XML main JSON to XML java 84    when I try to call from main the following lines   Model subProcessModel   getModelByModelGroup 1112   System out println subProcessModel getElement   getNote       I implemented the getModelByModelGroup int modelgroupid  method firstly like this    public static Model getModelByModelGroup int modelGroupId  boolean openTransaction         Session session   SessionFactoryHelper getSessionFactory   getCurrentSession             Transaction tx   null       if  openTransaction            tx   session getTransaction               String responseMessage            try           if  openTransaction                tx begin                      Query query   session createQuery  from Model where modelGroup id    modelGroupId            query setParameter  modelGroupId   modelGroupId            List lt Model gt  modelList    List lt Model gt  query list             Model model   null           for  Model m   modelList                if  m getModelType   getId      3                    model   m                  break                                   if  model    null                Object   arrModels   modelList toArray                if  arrModels length    0                    throw new Exception  Non esiste                                model    Model arrModels 0                      if  openTransaction                tx commit                       return model        catch Exception ex           if  openTransaction               tx rollback                    ex printStackTrace           if  responseMessage compareTo        0               responseMessage    Error    ex getMessage                    return null            and got the exception  Then a friend suggested me to always test the session and get the current session to avoid this error  So I did this   public static Model getModelByModelGroup int modelGroupId        Session session   null      boolean openSession   session    null      Transaction tx   null      if  openSession            session   SessionFactoryHelper getSessionFactory   getCurrentSession             tx   session getTransaction              String responseMessage            try           if  openSession                tx begin                      Query query   session createQuery  from Model where modelGroup id    modelGroupId            query setParameter  modelGroupId   modelGroupId            List lt Model gt  modelList    List lt Model gt  query list             Model model   null           for  Model m   modelList                if  m getModelType   getId      3                    model   m                  break                                   if  model    null                Object   arrModels   modelList toArray                if  arrModels length    0                    throw new RuntimeException  Non esiste                               model    Model arrModels 0                if  openSession                    tx commit                              return model            catch RuntimeException ex                if  openSession                    tx rollback                              ex printStackTrace                if  responseMessage compareTo        0                    responseMessage    Error    ex getMessage                              return null                              but still  get the same error   I have been reading a lot for this error and found some possible solutions  One of them was to set lazyLoad to false but I am not allowed to do this that s why I was suggested to control the session

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Faced the same Exception in different use case     Use Case   Try to read data from DB with DTO projection   Solution  Use get method instead of load   Generic Operation  public class HibernateTemplate   public static Object loadObject Class lt   gt  cls  Serializable s        Object o   null      Transaction tx   null      try           Session session   HibernateUtil getSessionFactory   openSession            tx   session beginTransaction            o   session load cls  s     change load to get           tx commit            session close          catch  Exception e            e printStackTrace              return o         Persistence Class  public class Customer     Id  GeneratedValue strategy   GenerationType IDENTITY   Column name    Id   private int customerId    Column name    Name   private String customerName    Column name    City   private String city     constructors   setters and getters      CustomerDAO interface  public interface CustomerDAO            public CustomerTO getCustomerById int cid            Entity Transfer Object Class  public class CustomerTO    private int customerId   private String customerName   private String city     constructors   setters and getters      Factory Class  public class DAOFactory    static CustomerDAO customerDAO  static       customerDAO   new HibernateCustomerDAO       public static CustomerDAO getCustomerDAO         return customerDAO         Entity specific DAO  public class HibernateCustomerDAO implements CustomerDAO     Override public CustomerTO getCustomerById int cid        Customer cust    Customer  HibernateTemplate loadObject Customer class  cid       CustomerTO cto   new CustomerTO cust getCustomerId    cust getCustomerName    cust getCity         return cto         Retrieving data  Test Class  CustomerDAO cdao   DAOFactory getCustomerDAO    CustomerTO c1   cdao getCustomerById 2   System out println  CustomerName - gt      c1 getCustomerName        CustomerCity - gt      c1 getCity       Present Data    Query and output generated by Hibernate System  Hibernate  select customer0  Id as Id1 0 0   customer0  City as City2 0 0   customer0  Name as Name3 0 0  from CustomerLab31 customer0  where customer0  Id    CustomerName -  Cody  CustomerCity -  LA

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If you using Spring mark the class as  Transactional  then Spring will handle session management    Transactional public class MyClass               By using  Transactional  many important aspects such as transaction propagation are handled automatically  In this case if another transactional method is called the method will have the option of joining the ongoing transaction avoiding the  no session  exception   WARNING If you do use  Transactional  please be aware of the resulting behavior  See this article for common pitfalls  For example  updates to entities are persisted even if you don t explicitly call save

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I encountered the same issue  I think another way to fix this is that you can change the query to join fetch your Element from Model as follows   Query query   session createQuery  from Model m join fetch m element where modelGroup id    modelGroupId

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If you are using Grail s Framework  it s simple to resolve lazy initialization exception by using Lazy keyword on specific field in Domain Class   For-example    class Book       static belongsTo    author  Author      static mapping             author lazy  false           Find further information here

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This means that the object which you are trying to access is not loaded  so write a query that makes a join fetch of the object which you are trying to access    Eg   If you are trying to get ObjectB from ObjectA where ObjectB is a foreign key in ObjectA   Query    SELECT objA FROM ObjectA obj JOIN FETCH obj objectB objB

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This exception because of when you call session getEntityById    the session will be closed  So you need to re-attach the entity to the session  Or Easy solution is just configure default-lazy  false   to your entity hbm xml or if you are using annotations just add  Proxy lazy false  to your entity class

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There are several good answers here that handle this error in a broad scope  I ran into a specific situation with Spring Security which had a quick  although probably not optimal  fix   During user authorization  immediately after logging in and passing authentication  I was testing a user entity for a specific authority in a custom class that extends SimpleUrlAuthenticationSuccessHandler   My user entity implements UserDetails and has a Set of lazy loaded Roles which threw the  org hibernate LazyInitializationException - could not initialize proxy - no Session  exception  Changing that Set from  fetch FetchType LAZY  to  fetch FetchType EAGER  fixed this for me

User · Answer

You can try to set    lt property name  hibernate enable lazy load no trans  gt true lt  property gt    in hibernate cfg xml or persistence xml  The problem to keep in mind with this property are well explained here

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Do the following changes in servlet-context xml       lt beans property name  hibernateProperties  gt           lt beans props gt                lt beans prop key  hibernate enable lazy load no trans  gt true lt  beans prop gt            lt  beans props gt       lt  beans property gt

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This means you are using JPA or hibernate in your code and performing modifying operation on DB without making the business logic transaction  So simple solution for this is mark your piece of code  Transactional

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I was getting the same error for a one to many relationships for below annotation     OneToMany mappedBy  department   cascade   CascadeType ALL    Changed as below after adding fetch FetchType EAGER  it worked for me    OneToMany mappedBy  department   cascade   CascadeType ALL  fetch FetchType EAGER

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In my case a misplaced session clear   was causing this problem

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if you use spring data jpa   spring boot you can add this line in application properties  spring jpa properties hibernate enable lazy load no trans true

User · Answer

What is wrong here is that your session management configuration is set to close session when you commit transaction  Check if you have something like    lt property name  current session context class  gt thread lt  property gt    in your configuration   In order to overcome this problem you could change the configuration of session factory or open another session and only than ask for those lazy loaded objects  But what I would suggest here is to initialize this lazy collection in getModelByModelGroup itself and call   Hibernate initialize subProcessModel getElement       when you are still in active session   And one last thing  A friendly advice  You have something like this in your method   for  Model m   modelList        if  m getModelType   getId      3            model   m          break            Please insted of this code just filter those models with type id equal to 3 in the query statement just couple of lines above    Some more reading   session factory configuration  problem with closed session

User · Answer

The best way to handle the LazyInitializationException is to use the JOIN FETCH directive  Query query   session createQuery  quot  quot  quot      select m     from Model m     join fetch m modelType     where modelGroup id    modelGroupId      quot  quot  quot      Anyway  DO NOT use the following Anti-Patterns as suggested by some of the answers   Open Session in View hibernate enable lazy load no trans  Sometimes  a DTO projection is a better choice than fetching entities  and this way  you won t get any LazyInitializationException

User · Answer

you could also solved it by adding lazy false into   into your   hbm xml file or you can init your object in Hibernate init Object  when you get object from db

User · Answer

If you are using JPQL  use JOIN FETCH is the easiest way  http   www objectdb com java jpa query jpql from LEFT OUTER INNER JOIN FETCH

User · Answer

This happened to me when I was already using  Transactional value      and was using multiple transaction managers  My forms were sending back data that already had  JsonIgnore on them  so the data being sent back from forms was incomplete  Originally I used the anti pattern solution  but found it was incredibly slow  I disabled this by setting it to false  spring jpa properties hibernate enable lazy load no trans false  The fix was to ensure that any objects that had lazy-loaded data that weren t loading were retrieved from the database first  Optional lt Object gt  objectDBOpt   objectRepository findById object getId      if  objectDBOpt isEmpty             Throw error   else       Object objectFromDB   objectDBOpt get       In short  if you ve tried all of the other answers  just make sure you look back to check you re loading from the database first if you haven t provided all the  JsonIgnore properties and are using them in your database query

User · Answer

uses session get   class  id   but do not load function

[java] How to fix org.hibernate.LazyInitializationException - could not initialize proxy - no Session

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