CODEWITHSUNDEEP
javasqljpajpql
pedro
pedro

Reputation: 427

JPQL Query - java.lang.String cannot be cast to model.xxx

ACTUAL FULL ERROR

java.lang.ClassCastException: java.lang.String cannot be cast to model.Persone

--

Hi al, I'm very new to JPQL and I'm trying to write a quite simple JPQL Query without luck.

I have a database table named persone with the a String nome column.

The query I'd like to translate is SELECT Nome FROM persone

--

Here's the entity

@Entity
public class Persone implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name="id_persona")
    private int idPersona;

    private String cognome;

    private Timestamp data_nascita;

    @Column(name="nome")
    private String nome;
}

--

This is a snippet of the query execution method. I tried to modify it setting the return (and everything else) to String instead of List, but then I can't manage to get the right method instead of getResultList().

public static List<Persone> selectAllPersone(){
    Query selectAll = em.createQuery("SELECT p FROM Persone p");
    @SuppressWarnings("unchecked")
    List<Persone> list = selectAll.getResultList();
    return list;
}

--

And here's me failing at coding

Query selectAll = em.createQuery("SELECT p.nome FROM Persone p");

What could this error be due to?

Upvotes: 1

Views: 1230

Answers (3)

xrcwrn
xrcwrn

Reputation: 5327

    Query selectAll = em.createQuery("SELECT p.nome FROM Persone p");

As you code shows you are selecting only string from query not all person object Following query will return person object

Query selectAll = em.createQuery("SELECT p FROM Persone p");
  List<Persone> list = selectAll.getResultList();

If you want to select only name from person.A name is string type and it will return List<String> 

Query selectAll = em.createQuery("SELECT p.nome FROM Persone p");
List<String> result = selectAll.getResultList();

Upvotes: 1

pedro
pedro

Reputation: 427

I managed to sort it out and have it work for me. I just created a new method which returns a List<String> and it went fine. 

public static List<String> selectNome(){
    Query selectAll = em.createQuery("SELECT p.nome FROM Persone p");
    @SuppressWarnings("unchecked")
    List<String> qnome = selectAll.getResultList();
    return qnome;
}

Thank you guys for your help :)

Upvotes: 0

Jure Kolenko
Jure Kolenko

Reputation: 809

You are selecting the name (p.nome) which is a string, so you'll get a string back.

If you want a whole person to be returned, select the whole person (SELECT p FROM Personne p).

Upvotes: 4

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