JPA映射，父级到子级和子级到父级，具有两个类和抽象类

Question

我有两个从抽象类继承的类，它们有父子关系。

所以我使用了注释OneToOne和ManyToOne，但是子类中的父实体总是为空。有人能帮我吗，我花了几个小时谷歌和测试了许多conf，但没有成功。

这些是我的类中的代码：

public @Table(name="flowentity") @Entity abstract class FlowEntity {

final static Logger log = LoggerFactory.getLogger(FlowEntity.class);

//Globals informations concerning the flow state
private @Id @GeneratedValue(strategy = GenerationType.IDENTITY) Integer flowId = 0;
private String flowName;

private @OneToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL) 
        Set<PeopleEntity> actorSet = new HashSet<>();


//Global parameters for most of flows
//Organizational parameters
private @OneToOne(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
        @JoinColumn(name="organisationalEntity_Id")
        OrganisationalEntity organisationalEntity;

...

public @Table(name="ams_newCPEntity") @Entity class NewMultiCPEntity  extends FlowEntity {

private @OneToMany(targetEntity=NewCPEntity.class, fetch=FetchType.EAGER, cascade=CascadeType.ALL,mappedBy="parent") 
        Set<NewCPEntity> cpList = new HashSet<NewCPEntity>();

//Constructor
    public NewMultiCPEntity(){
        setFlowName(EnumFlow.N_CP_M.getFlowAcronym());
    }

...

public @Table(name="ams_newCPEntity") @Entity class NewCPEntity extends FlowEntity {

final static Logger log = LoggerFactory.getLogger(NewCPEntity.class);

private boolean formNCPValidated;

private @ManyToOne @JoinColumn(name="parent_Id", nullable=false)
        NewMultiCPEntity parent;

public NewCPEntity(){
    log.debug("Instanciation of a new CP");
    setFlowName(EnumFlow.N_CP.getFlowAcronym());
}

public @Override OrganisationalEntity getOrganisationalEntity(){
    return parent.getOrganisationalEntity();
}

...

如果我不添加@JoinCol列注释，JPA会创建一个关联表，但无法检索父级，而关联可以直接通过在数据库中请求来完成。

非常感谢你的帮助。

祝好

Answer 1

谢谢Chris的评论，你是对的，我忘记更改表的名称了。我认为这不是问题，因为继承映射在一个带有DTYPE鉴别器列的表流实体中。

最后，我通过在添加新子级时设置父属性来解决问题，如下所示：

public @Table @Entity class NewMultiCPEntity  extends FlowEntity {

    private @OneToMany(targetEntity=NewCPEntity.class, fetch=FetchType.EAGER, cascade=CascadeType.ALL) 
            List<NewCPEntity> cpList = new ArrayList<>();

    //Constructor
        public NewMultiCPEntity(){
            setOrganisationalEntity(new OrganisationalEntity());
            setFlowName(EnumFlow.N_CP_M.getFlowAcronym());
        }

    public List<NewCPEntity> getNCPList(){
        if(cpList == null){
            cpList = new ArrayList<>();
        }
        if(cpList.isEmpty()){
            addCPEntity(new NewCPEntity());
        }
        return Collections.unmodifiableList(cpList);}

    public boolean removeCPEntity(NewCPEntity entity){
        return cpList.remove(entity);
    }
    public boolean addCPEntity(NewCPEntity entity){
        entity.setParent(this);
        entity.setOrganisationalEntity(this.getOrganisationalEntity());
        return cpList.add(entity);
    }

我移除了子级中对getOrganizationalEntity的重写：

public @Table @Entity class NewCPEntity extends FlowEntity {

    final static Logger log = LoggerFactory.getLogger(NewCPEntity.class);


    private @ManyToOne(targetEntity=NewMultiCPEntity.class,cascade=CascadeType.ALL)
            NewMultiCPEntity parent;

    public NewCPEntity(){
        log.debug("Instanciation of a new CP");
        setFlowName(EnumFlow.N_CP.getFlowAcronym());
    }

    public NewMultiCPEntity getParent() {
        return parent;
    }

    public void setParent(NewMultiCPEntity parent){
        this.parent = parent;
    }

祝好