在JPA中联接2个表的CreateQuery

Question

I have this error

The collection-valued path 'c.medecin' cannot be resolved to a valid association field
The state field path 'm.id' cannot be resolved to a valid type.

when I execute this request

createQuery("select c from Creneaux c join c.medecin m where m.id=:idMedecin").setParameter("idMedecin", medecin.getId());

I use these 2 tables : MEDECINS(ID) and CRENEAUX(ID, ID_MEDECIN)

@Entity
@Table(name = "medecins")
@XmlRootElement
public class Medecins implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "ID")
    private Long id;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "medecin"/*"idMedecin"*/)
    private transient List<Creneaux> creneauxList;
}

and

@Entity
@Table(name = "creneaux")
public class Creneaux implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "ID")
    private Long id;
    @ManyToOne(fetch=FetchType.LAZY)
    @JoinColumn(name="ID_MEDECIN")
    private transient Medecins medecin;

    @Column(name = "ID_MEDECIN")
    private BigInteger idMedecin;

I begin in JPA, so I a not sure about all the code. I think the Query is correct, but I don't know how to annotate the entities to make the Query valid. Thanks

Answer 1

I wonder why adding the last attribute in the second Entity that is: idMedecin while you've already joined the two entities to each others. Maybe you should omit it. If the purpose of the query is to select all the creneaux related to the given medecin, then you ought to change the query to:

createQuery("SELECT c FROM Creneaux c WHERE c.medecin.id = :idMedecin").setParameter("idMedecin", medecin.getId());

Where medecin.getId() should be provided before the query's execution.

Answer 2

That's because the Creneaux.medecin field is transient . Transient fields are ignored by JPA.

Another thing is that you don't have two join these two entities. If you want to filter by Medecin ID it's enough to execute a query as @Omar described.