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JPA - Making @OneToOne relationship mandatory by setting optional=false

@OneToOne annotation specifies an association to another entity that has one-to-one multiplicity. Following example demonstrates that setting @OneToOne(optional=false) makes the association mandatory. For a mandatory association, the target entity cannot be persisted when it's associated reference is null.

The default value of 'optional' element is true.

Example Project

Dependencies and Technologies Used:

  • h2 1.4.193: H2 Database Engine.
  • hibernate-core 5.2.8.Final: The core O/RM functionality as provided by Hibernate.
    Implements javax.persistence:javax.persistence-api version 2.1
  • JDK 1.8
  • Maven 3.3.9
jpa-one-to-one-optional-example Select All Download
  • jpa-one-to-one-optional-example
    • src
      • main
        • java
          • com
            • logicbig
              • example
                • EntityA.java
          • resources
            • META-INF

    Running the main class (ExampleMain.java) will throw following exception.

    Output

    Caused by: javax.persistence.PersistenceException: org.hibernate.PropertyValueException: not-null property references a null or transient value : com.logicbig.example.EntityA.entityB
    	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:147)
    	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:155)
    	at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:162)
    	at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:780)
    	at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:758)
    	at com.logicbig.example.ExampleMain.main(ExampleMain.java:20)
    	... 6 more
    Caused by: org.hibernate.PropertyValueException: not-null property references a null or transient value : com.logicbig.example.EntityA.entityB
    	at org.hibernate.engine.internal.Nullability.checkNullability(Nullability.java:92)
    	at org.hibernate.action.internal.AbstractEntityInsertAction.nullifyTransientReferencesIfNotAlready(AbstractEntityInsertAction.java:115)
    	at org.hibernate.action.internal.AbstractEntityInsertAction.makeEntityManaged(AbstractEntityInsertAction.java:124)
    	at org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:283)
    	at org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:258)
    	at org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:245)
    	at org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:326)
    	at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:275)
    	at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
    	at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
    	at org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67)
    	at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189)
    	at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132)
    	at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58)
    	at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:773)
    	... 8 more

    See also

    JPA - OneToOne relationship