错误：org.hibernate.PersistentObjectException：分离的实体传递给持久化

Question

I'm working on Spring-boot+ ReactJs application. BAsically I have 2 Entities ( Brand and Family) which have One to Many Relationship.

@Entity
@Table(name = "brands")
public class Brand extends UserDateAudit {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @NotBlank
    @Size(max = 140)
    private String name;

    @Lob @JsonProperty("image")
    private byte[] image;

    @OneToMany
    private Set<Family> family;

and

@Entity
@Table(name = "family")
public class Family extends UserDateAudit {
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Long id;

        @NotBlank
        @Size(max = 140)
        private String name;

        @JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
        @ManyToOne(fetch = FetchType.LAZY,cascade=CascadeType.ALL, optional = false)
        @JoinColumn(name = "brand_id")
        private Brand brand;

When I creating 'Family' object it throws following error.

org.hibernate.PersistentObjectException: detached entity passed to persist: com.example.polls.model.Brand
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:807) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:774) ~[hibernate-core-5.2.17.Final.jar:5.2.17.Final]

createFamily() is as follows.

public Family createFamily(@Valid FamilyRequest familyRequest) {
            Family family = new Family();
            family.setName(familyRequest.getName());
            family.setBrand(familyRequest.getBrand());
            return familyRepository.save(family);
        }

Through debuging I found the 'familyRequest' have both 'name' and 'Brand_id'

ReactJS:

 handleSubmit(event) {
        event.preventDefault();
      //  console.log('image: '+this.state.brand_id.text);
        const familyData = {
            name: this.state.name.text,
            brand: {id : this.state.brand_id.text}
        //    band_id: this.state.band_id
        };

        createFamily(familyData)
        .then(response => {
            this.props.history.push("/");
        }).catch(error => {
            if(error.status === 401) {
                this.props.handleLogout('/login', 'error', 'You have been logged out. Please login create family.');
            } else {
                notification.error({
                    message: 'Polling App',
                    description: error.message || 'Sorry! Something went wrong. Please try again!'
                });
            }
        });
    }

I'm not sure whether I set value for brand_id is correct. Please help me to solve this isssue.

Answer 1

Your mapping is incorrect. The one side of a bidirectional OneToMany must use the mappedBy attribute.

And cascading all operations on a ManyToOne makes no sense: when you create a family, you don't want to create its brand: it already exists. And when you delete a family, you don't want to delete its brand, since it's referenced by many other families.