I'm hitting 'org.hibernate.SessionException: collections cannot be fetched by a stateless session'

Solution Verified - Updated -

Environment

  • Java Persistence API (JPA)
  • Hibernate

Issue

  • The following error is raised when I enable lazy loading on a particular collection, the application code used to work before the change

    org.hibernate.SessionException: collections cannot be fetched by a stateless session

Resolution

The use of lazy loading in conjunction with stateless session are not compatible.  You either need to do one of two things

  1. Use a stateful Hibernate session
  2. Disable lazy loading for the involved assocation

Root Cause

The stateless hibernate session doesn't keep any first level cache nor acts as a persistence context. It is not able to handle loading on-demand.

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