Hibernate error: ids for this class must be manually assigned before calling save():

Question

``` Caused by: org.springframework.orm.hibernate3.HibernateSystemException: ids for this class must be manually assigned before calling save(): com.rfid.model.Role; nested exception is org.hibernate.id.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): com.rfid.model.Role at org.springframework.orm.hibernate3.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:676) at org.springframework.orm.hibernate3.HibernateAccessor.convertHibernateAccessException(HibernateAccessor.java:412) at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:424) at org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374) at org.springframework.orm.hibernate3.HibernateTemplate.saveOrUpdate(HibernateTemplate.java:748) at com.wfos.engine.wrapper.domain.impl.WrapperImpl.save(WrapperImpl.java:159) ... 47 more Caused by: org.hibernate.id.IdentifierGenerationExce…

Accepted Answer

Your `@Entity` class has a `String` type for its `@Id` field, so it can't generate ids for you.

If you change it to an auto increment in the DB and a `Long` in java, and add the `@GeneratedValue` annotation:

```
@Id
@Column(name="U_id")
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long U_id;
```

it will handle incrementing id generation for you.

Hibernate error: ids for this class must be manually assigned before calling save():

Solution

Problem