hibernate 非空属性引用空值或瞬态值

Question

每个人。我是 Hibernate 的新手，并且在对象持久化方面遇到了一些意想不到的麻烦。 以下是我的实体类的相关摘录：

TAAnalysis.java

public class TAnalysis implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Integer unAnalysis;

    @JoinColumn(name = "uninttest", referencedColumnName = "un_inttest", nullable = false)
    @ManyToOne(fetch = FetchType.EAGER, optional = false, cascade = CascadeType.ALL)
    private TIntTest tIntTest;

    @OneToOne(optional = false, mappedBy = "tAnalysis", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private TBaseComp tBaseComp;

    @OneToOne(optional = false, mappedBy = "tAnalysis", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private TWellTest tWellTest;

    @OneToOne(optional = false, mappedBy = "tAnalysis", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private TGasPart tGasPart;

    @OneToOne(optional = false, mappedBy = "tAnalysis", fetch = FetchType.EAGER, cascade = CascadeType.ALL)
    private TAddOnComp tAddOnComp;
}

TIntTest.java

public class TIntTest implements Serializable, ISimpleEntity {

    @Id
    @GeneratedValue (strategy = GenerationType.SEQUENCE)
    @Column (name = "un_inttest", nullable = false)
    private Integer unInttest;

    @OneToMany (cascade = CascadeType.ALL, mappedBy = "tIntTest")
    private Set<TAnalysis> tAnalysisSet;
}

TBaseComp.java

public class TBaseComp implements Serializable {

    @Id
    @Column(name = "un_analysis", nullable = false)
    private Integer unAnalysis;

    @MapsId
    @JoinColumn(name = "un_analysis", referencedColumnName = "un_analysis", nullable = false, insertable = false, updatable = false)
    @OneToOne(optional = false, fetch = FetchType.EAGER)
    private TAnalysis tAnalysis;
}

与 TAnalysis 有 [@OneToOne] 关系的其他类（TAddOnComp、TGasPart 和 TWellTest）（种“子类”）与 TBaseComp 共享相同的结构。

所有列出的关系都必须不为空。因此，当我坚持新的 TAnalysis 实例时，我必须为其指定 TIntTest 对象，并且还必须创建“子类”实例。我就是这样做的：

EntityManager em = emf.createEntityManager();
TAnalysis an = new TAnalysis();
TBaseComp baseComp = new TBaseComp();
TGasPart gasPart = new TGasPart();
TAddOnComp addInComp = new TAddOnComp();
TWellTest wellTest = new TWellTest();

an.setTBaseComp(baseComp);
an.setTGasPart(gasPart);
an.setTAddOnComp(addInComp);
an.setTWellTest(wellTest);

baseComp.setTAnalysis(an);
gasPart.setTAnalysis(an);
addInComp.setTAnalysis(an);
wellTest.setTAnalysis(an);

TIntTest intTest = em.find(TIntTest.class, 10);
an.setTIntTest(intTest);

an = em.merge(an);
//baseComp = em.merge(baseComp);
//gasPart = em.merge(gasPart);
//addOnComp = em.merge(addOnComp);
//wellTest = em.merge(wellTest);
//em.persist(an);
em.getTransaction().commit();

合并操作抛出异常

org.hibernate.PropertyValueException: not-null property references a null or transient value :   org.foladesoft.omnibus_client_maven.entities.TAnalysis.tIntTest"

我不明白为什么会发生这种情况，因为我指定了请求的属性值an.setTIntTest(intTest)；

为了解决我的问题，我使用 em.persist(an) 而不是合并，但在 commit 阶段遇到了另一个异常：PostgreSQL 的 外键违规异常 告诉我我正在尝试在将新记录插入 TAnalysis 之前将记录插入 TAddOnComp。

能否请您告诉我为什么会遇到这些问题以及如何使我的应用程序正常工作。

Answer 1

首先，因为这是您应该调用的新实体：

em.persist(an);

调用 em.persist(an) 时出现 FK 冲突的原因是 TAddOnComp 对其关联的 TAnalysis 一无所知，因此无法插入 FK。

对于双向关系，您始终需要在内存模型中维护关系的双方。然后 TAddOnComp 将具有对其关联的 TAnalysis 的引用，并且插入操作可以相应地获取和插入 FK。

TAnalysis an = new TAnalysis();
an.setTBaseComp(baseComp);
an.setTGasPart(gasPart);
//etc
baseComp.setAnalysis(an);
gasPart.setAnalysis(an);
//etc
em.persist(an);

理想情况下，您应该封装这些操作：

public class TAnalysis implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE)
    private Integer unAnalysis;

    private TAddOnComp tAddOnComp;

    public void setTAddOnComp(TAddOnComp tAddOnComp){
        this.tAddOnComp = tAddOnComp;

        if(! tAddOnComp.getTAnalysis != this){
            tAddOnComp.setTAnalysis(this);
        }

        // and do the same on the other side of the relationship
    }
}