JPA：外键作为 NamedQuery 中的参数

Question

我正在尝试Raadpleging从我的数据库中返回对象。这些对象包含 aPersoon和 a Les。我的目标是返回所有 Raadplegingen，其中 Les 的 ID 等于参数。我不确定如何在我的查询中执行此操作。我也不太确定我的第一个 namedQuery 是否也会返回 Persoon 和 Les 属性，或者我是否需要一个连接。正如您在下面看到的，我尝试使用这样的参数WHERE r.les  = :lesId，我认为这是不正确的。@Entity@Access(AccessType.PROPERTY)@Table(name = "Raadplegingen")@NamedQueries({    @NamedQuery(name = "ClubRaadpleging.getAlleRaadplegingen",            query = "SELECT r FROM ClubRaadpleging r"),    @NamedQuery(name = "ClubRaadpleging.findByLes",            query = "SELECT r FROM ClubRaadpleging r JOIN ClubLes l ON l.id =r.les.id WHERE r.les  = :lesId")})public class ClubRaadpleging implements Serializable {    private int id;    private ClubLes les;    private ClubPersoon persoon;    private Date datum;    public ClubRaadpleging() {    }    @Id    @GeneratedValue(strategy = GenerationType.IDENTITY)    @Column(name = "RaadplegingId")    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    @ManyToOne(cascade = CascadeType.PERSIST)    @JoinColumn(name = "LesId")    public ClubLes getLes() {        return les;    }    public void setLes(ClubLes les) {        this.les = les;    }    @ManyToOne(cascade = CascadeType.PERSIST)    @JoinColumn(name = "PersoonId")    public ClubPersoon getPersoon() {        return persoon;    }    public void setPersoon(ClubPersoon persoon) {        this.persoon = persoon;    }    @Temporal(TemporalType.DATE)    public Date getDatum() {        return datum;    }    public void setDatum(Date datum) {        this.datum = datum;    }}

Answer 1

ClubRaadpleging和之间不需要加入ClubLes。根据实体映射，JPA 本身已经完成了这项工作。

您可以尝试以这种方式简化 NamedQuery：

@Entity

@Access(AccessType.PROPERTY)

@Table(name = "Raadplegingen")

@NamedQueries({

    @NamedQuery(name = "ClubRaadpleging.getAlleRaadplegingen",

            query = "SELECT r FROM ClubRaadpleging r"),

    @NamedQuery(name = "ClubRaadpleging.findByLes",

            query = "SELECT r FROM ClubRaadpleging r WHERE r.les.id  = :lesId")

})

public class ClubRaadpleging implements Serializable {