java - 为什么我的结果列表是空的？

Question

为什么我的结果列表是空的？ 我有什么错吗？我的表中有两行，但结果始终为空。

表1:

表2:

参数电话(我在 Debug模式下看到)与表中相同。

List<IAppEntity> list = entityManager.createQuery(
                "SELECT a FROM IAppsFriends c" +
                        " JOIN c.apps a" +
                        " WHERE c.phone=:phone")
                .setParameter("phone", phone).getResultList();

IAppsFriends:

    @Entity
        @Table(name = "IAppsFriends")
        public class IAppsFriends {

            @GeneratedValue
            @Id
            private int id;

            @OneToMany(mappedBy = "packageName")
            private List<IAppEntity> apps;

            private String phone;

            public int getId() {
                return id;
            }

            public void setId(int id) {
                this.id = id;
            }

            public List<IAppEntity> getApps() {
                return apps;
            }

            public void setPackageName(List<IAppEntity> apps) {
                this.apps = apps;
            }

            public String getPhone() {
                return phone;
            }

            public void setPhone(String phone) {
                this.phone = phone;
            }

        }

IAppEntety:

@Entity
@Table(name = "IApp")
public class IAppEntity {

    @Id
    private String packageName;

    public IAppsFriends getFriends() {
        return friends;
    }

    public void setFriends(IAppsFriends friends) {
        this.friends = friends;
    }

    @ManyToOne
    @JoinColumn(name="packageName", insertable = false, updatable = false)
    private IAppsFriends friends;

    private String icon;

    private String name;

    public String getPackageName() {
        return packageName;
    }

    public void setPackageName(String packageName) {
        this.packageName = packageName;
    }

    public String getIcon() {
        return icon;
    }

    public void setIcon(String icon) {
        this.icon = icon;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

Answer 1

您的映射不正确:

@OneToMany(mappedBy = "packageName")
private List<IAppEntity> apps;

这意味着这个 OneToMany 关联是在 IAppEntity 实体的 packageName 字段上声明的 ManyToOne 关联的反面。但字段 packageName 声明为

@Id
private String packageName;

所以它根本不是ManyToOne。