query.getResultList 中的 ClassCastException

Question

I have a function that runs a query on a postrgresql database using hibernate.

When I call query.getResultList() I get this error:

java.lang.ClassCastException: class java.lang.String cannot be cast to class java.util.UUID (java.lang.String and java.util.UUID are in module java.base of loader 'bootstrap')

at org.hibernate.type.descriptor.java.UUIDTypeDescriptor.unwrap(UUIDTypeDescriptor.java:20) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final] at org.hibernate.type.PostgresUUIDType$PostgresUUIDSqlTypeDescriptor$1.doBind(PostgresUUIDType.java:74) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final] at org.hibernate.type.descriptor.sql.BasicBinder.bind(BasicBinder.java:73) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final] at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:276) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final] at org.hibernate.type.AbstractStandardBasicType.nullSafeSet(AbstractStandardBasicType.java:271) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]

Java function:

@Override
public StudentEntity findByAccountId(UUID accountId) {
    SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
    Session session = sessionFactory.openSession();
    Query query = session.createQuery("select _student from StudentEntity _student where _student.accountId = :id_cont");
    query.setParameter("id_cont", accountId.toString());
    System.out.println(query.getResultList());
    return new StudentEntity();
}

Student entity object definition:

@Table(name = "Studenti")
@Entity(name = "StudentEntity")
public class StudentEntity implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "genname")
    @SequenceGenerator(name = "genname", sequenceName = "seqname", allocationSize = 1)
    @Column(name = "Id")
    private UUID Id;

    @Column(name = "Nume")
    private String firstName;

    @Column(name = "Prenume")
    private String lastName;

    @Column(name = "An")
    private int year;

    @Column(name = "Grupa")
    private String grupa;

    @Column(name = "Id_cont")
    private UUID accountId;
}

Answer 1

Update your entity to this by changing the data type of the accountId to String from UUID :

@Table(name = "Studenti")
@Entity(name = "StudentEntity")
public class StudentEntity implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "genname")
    @SequenceGenerator(name = "genname", sequenceName = "seqname", allocationSize = 1)
    @Column(name = "Id")
    private UUID Id;

    @Column(name = "Nume")
    private String firstName;

    @Column(name = "Prenume")
    private String lastName;

    @Column(name = "An")
    private int year;

    @Column(name = "Grupa")
    private String grupa;

    @Column(name = "Id_cont")
    private String accountId;
}

or

Change the java function to this :

@Override
public StudentEntity findByAccountId(UUID accountId) {
    SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
    Session session = sessionFactory.openSession();
    Query query = session.createQuery("select _student from StudentEntity _student where _student.accountId = :id_cont");
    query.setParameter("id_cont", accountId); // send the parameter as it is 
    System.out.println(query.getResultList());
    return new StudentEntity();
}