'Direct self-reference leading to cycle' 杰克逊与遗产

'Direct self-reference leading to cycle' Jackson and inheritance

我有一个 class 像这样的东西:

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@Audited
@DiscriminatorColumn(name = "tipo_hito")
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = { "idHito" })
@XmlRootElement(name = "Hito")
public abstract class Hito implements Ordenable {
    @Id
    @GeneratedValue(strategy= GenerationType.IDENTITY)
    @Column(name = "idhito", nullable = false)
    private Long idHito;

    public Long getIdHito() { return idHito; }

    public void setIdHito(Long idHito) { this.idHito = idHito; }
}

还有一个 class 扩展 class 以上

@MappedSuperclass
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = {..., "successors", "predecessors", ...})
@XmlRootElement(name = "HitoOrdenable")
public abstract class HitoOrdenable extends Hito {

    @XmlElement(name = "predecessors")
    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "succession", joinColumns = { @JoinColumn(name = "idpredecessor") }, inverseJoinColumns = { @JoinColumn(name = "idsuccessor") })
    private Set<Hito> predecessors;

    @XmlElement(name = "successors")
    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "succession", joinColumns = { @JoinColumn(name = "idsuccessor") }, inverseJoinColumns = { @JoinColumn(name = "idpredecessor") })
    private Set<Hito> successors;

    // More code...
}

现在,当我尝试获取 HitoOrdenable 时出现错误。因为例如我可以有:

Hito1
  Hito2-SuccessorOf1
  Hito3-SuccessorOf1
    Hito4-SuccessorOf3
Hito5
  Hito6-SuccessorOf5

所以,当我得到 Hito1 时,它有继任者 Hito2Hito3。但是当我得到 Hito2 时,它的前身是 Hito1。所以开始一个"infinite cycle".

准确的错误是:

com.fasterxml.jackson.databind.JsonMappingException: Direct self-reference leading to cycle (through reference chain: ar.gob.buenosaires.esb.domain.message.ProyectoRespMsg["proyectos"]->java.util.ArrayList[5]->ar.gob.buenosaires.domain.Proyecto["obras"]->org.hibernate.collection.internal.PersistentBag[0]->ar.gob.buenosaires.domain.Obra["hitos"]->org.hibernate.collection.internal.PersistentBag[0]->ar.gob.buenosaires.domain.HitoObra["hitoOrdenable"])

我尝试在 predecessors 中设置 @JsonIgnore 但它不起作用。

经过几天的尝试。我们找到的唯一解决方案是添加 @JsonIgnoreProperties({"predecessors"})@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="idHitoAux")

HitoOrdenable.java

  @MappedSuperclass
  @XmlType(propOrder = {..., "successors", "predecessors", ...})
  @XmlAccessorType(XmlAccessType.FIELD)
  @JsonIgnoreProperties({ "predecessors" })
  @JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="idHitoAux")

Hito.java

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@Audited
@XmlAccessorType(XmlAccessType.FIELD)
@XmlType(propOrder = { "idHito", "tipoHito"})
@JsonIgnoreProperties({"idHitoAux", "hibernateLazyInitializer", "handler"})
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.EXISTING_PROPERTY, visible = true, property = "tipoHito")
@JsonSubTypes({
        @JsonSubTypes.Type(name = "hito_obra", value = HitoObra.class),
        @JsonSubTypes.Type(name = "hito_proyecto", value = HitoProyecto.class)
})<

使用 JsonIgnoreProperties 我们可以防止后继者和前任之间的无限循环,使用 @JsonIdentityInfo 是因为如果我们使用 "idHito" 而不是 "idHitoAux" (它等于 idHito),Hibernate 转换了 idHito为空。因此 "idHitoAux" Hibernate 可以识别列表中的每个对象。

PD:在该解决方案之后我们遇到了反序列化 abstract class Hito 的问题,因此我们的解决方案是添加 @JsonSubTypes.

您好!