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

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.IdentifierGenerationException: ids for this class must be manually assigned before calling save(): com.rfid.model.Role
    at org.hibernate.id.Assigned.generate(Assigned.java:53)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:121)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:685)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:677)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:673)
    at org.springframework.orm.hibernate3.HibernateTemplate$16.doInHibernate(HibernateTemplate.java:751)
    at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:419)
    ... 50 more
    WARN [21:14:21] (CommonsLoggingOutput.java:59): - --Erroring: batchId[1] message[java.lang.reflect.UndeclaredThrowableException]

My class is like this:

@Entity
@javax.persistence.Table(name="Role")
@Table(appliesTo = "Role")
public class Role {

@Id  
@Column(name="U_id")
public String U_id;

public String U_pwd;

public String U_account;

public String U_mode;

public String U_status;


public String getU_pwd() {
    return U_pwd;
}

public void setU_pwd(String u_pwd) {
    U_pwd = u_pwd;
}

public String getU_account() {
    return U_account;
}

public void setU_account(String u_account) {
    U_account = u_account;
}

public String getU_id() {
    return U_id;
}

public void setU_id(String u_id) {
    U_id = u_id;
}

public String getU_mode() {
    return U_mode;
}

public void setU_mode(String u_mode) {
    U_mode = u_mode;
}

public String getU_status() {
    return U_status;
}

public void setU_status(String u_status) {
    U_status = u_status;
}

}

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.

For hibernate it is important to know that your object WILL have an id, when you want to persist/save it. Thus, make sure that

    private String U_id;

will have a value, by the time you are going to persist your object. You can do that with the @GeneratedValue annotation or by assigning a value manually.

In the case you need or want to assign your id's manually (and that's what the above error is actually about), I would prefer passing the values for the fields to your constructor, at least for U_id, e.g.

  public Role (String U_id) { ... }

This ensures that your object has an id, by the time you have instantiated it. I don't know what your use case is and how your application behaves in concurrency, however, in some cases this is not recommended. You need to ensure that your id is unique.

Further note: Hibernate will still require a default constructor, as stated in the hibernate documentation. In order to prevent you (and maybe other programmers if you're designing an api) of instantiations of Role using the default constructor, just declare it as private.

Here is what I did to solve just by 2 ways:

1. make ID column as int type

2. if you are using autogenerate in ID dont assing value in the setter of ID. If your mapping the some then sometimes autogenetated ID is not concedered. (I dont know why)

3. try using @GeneratedValue(strategy=GenerationType.SEQUENCE) if possible

Resolved this problem using a Sequence ID defined in Oracle database.

ORACLE_DB_SEQ_ID is defined as a sequence for the table. Also look at the console to see the Hibernate SQL that is used to verify.

@Id
@Column(name = "MY_ID", unique = true, nullable = false)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "id_Sequence")
@SequenceGenerator(name = "id_Sequence", sequenceName = "ORACLE_DB_SEQ_ID")
Long myId;