object references an unsaved transient instance: how to flush or return saved object

Question

I use Spring 3.2.3 and Hibernate 4.2.3 and JDK 7. I have a simple entity: ``` @Entity public class Language { @Id @GeneratedValue private long id; @Column(nullable = false, length = 3, unique = true) private String code; } ``` I saved an instance of this entity using a `@Service` annotated class with a `@Transactional` annotated method which uses a DAO which saves the entity with ``` sessionFactory.getCurrentSession().save(object); ``` After that I used the saved `Language` entity for creating `EntityX`, which used it in an `ManyToOne` relation ... ``` lang=new Language(); // ... languageService.saveLanguage(lang); e=new EntityX(); // ... e.setLanguage(lang); otherService.saveEntity(e); ``` and `EntityX` is defined as ... ``` @Entity public class EntityX { @ManyToOne @JoinColumn(nullable = false) private Language language; // ... } ``` I always get the exception ``` Exception in thread "main" org.hibernate.TransientObjectException: object references an unsaved transient instance - sav…

Accepted Answer

Is you code in a single `@Transactional` method? If not the problem can be that, after any call to service method, transaction will be commit and session cleared. When you try to save entity, language object is not detected in session and managed as transient instance and give the error.

In case your code is under single transaction did you try a `flush()` before saving entity to force Hibernate store `Language` to database and assign it a valid `@Id`entifier?

After all - IMHO - if you have a dependency from Entity and Language the best choice is:

```
@ManyToOne(cascade = CascadeType.ALL)
private Language language;
```

and change your code as:

```
e=new EntityX();
Language lang = new Language();
// ...
e.setLanguage(lang);
otherService.saveEntity(e);
```

and you don't need to persist entity in two steps (language + entity); manage language+entity as single item

PS: The save(...) method(s) of org.hibernate.Session does not return the saved object because the object will remain the same (reference doesn't change), just object properties changes (like the one marked this `@Id`, for example)!

EDIT: Make an object persistent (session.save() it I mean) don't result in a immediate insert/update; without cascade hint Hibernate look doesn't detect dependency between EntityX and Language and doesn't perform a sql insert of Language before saving EntityX. languageService.save(language) call doesn't perform session.flush() because you are under same `@Transactional` and without session.commit() no session.flush() is performed and best option is that Language object is still marked as transient. You can do a check: extract services save code (language entityX) and put all in single `@Transactional` and check if Hibernate still give you error. My best option is still perform a flush() in the middle or change your mapping, no other way

object references an unsaved transient instance: how to flush or return saved object

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