JPA：外键未从父主键插入子节点

Question

子外键引用为空。这个外键只是父表的主键。

我下面有两个表，其中有@OneToMany（父）和@ManyToOne（子）映射。记录插入到父项以及子项中，子项中的外键值除外。

下面的确认中有什么遗漏吗？

package com.springboot.model;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import static javax.persistence.GenerationType.IDENTITY;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import com.fasterxml.jackson.annotation.JsonBackReference;
import com.fasterxml.jackson.annotation.JsonIdentityInfo;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonManagedReference;
import com.fasterxml.jackson.annotation.ObjectIdGenerators;

@Entity
@Table(name = "app_user", catalog = "testdb")
@JsonIdentityInfo(generator=ObjectIdGenerators.PropertyGenerator.class, property="id")
public class AppUser implements java.io.Serializable {

    private Integer id;
    private Rank rank;
    private Trainingstatus trainingstatus;
    private String name;
    private int age;
    private double salary;
    private Set<Address> addresses = new HashSet<Address>(0);

    public AppUser() {
    }

    public AppUser(Rank rank, Trainingstatus trainingstatus, String name, int age, double salary) {
        this.rank = rank;
        this.trainingstatus = trainingstatus;
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public AppUser(Rank rank, Trainingstatus trainingstatus, String name, int age, double salary,
            Set<Address> addresses) {
        this.rank = rank;
        this.trainingstatus = trainingstatus;
        this.name = name;
        this.age = age;
        this.salary = salary;
        this.addresses = addresses;
    }

    @Id
    @GeneratedValue(strategy = IDENTITY)

    @Column(name = "id", unique = true, nullable = false)
    public Integer getId() {
        return this.id;
    }

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

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "rankId", nullable = false)
    //@JsonManagedReference(value="rank")

    public Rank getRank() {
        return this.rank;
    }

    public void setRank(Rank rank) {
        this.rank = rank;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "trainingStatusId", nullable = false)
    //@JsonManagedReference(value="trainingstatus")
    /*@JsonBackReference
    @JsonIgnore*/
    public Trainingstatus getTrainingstatus() {
        return this.trainingstatus;
    }

    public void setTrainingstatus(Trainingstatus trainingstatus) {
        this.trainingstatus = trainingstatus;
    }

    @Column(name = "name", nullable = false, length = 30)
    public String getName() {
        return this.name;
    }

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

    @Column(name = "age", nullable = false)
    public int getAge() {
        return this.age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    @Column(name = "salary", nullable = false, precision = 22, scale = 0)
    public double getSalary() {
        return this.salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    @OneToMany(fetch = FetchType.LAZY, mappedBy = "appUser" , cascade = CascadeType.ALL)
    public Set<Address> getAddresses() {
        return this.addresses;
    }

    public void setAddresses(Set<Address> addresses) {
        this.addresses = addresses;
    }

}



package com.springboot.model;
// Generated 29 Apr, 2018 9:46:33 PM by Hibernate Tools 4.3.5.Final

    import java.util.Date;

    import javax.persistence.CascadeType;
    import javax.persistence.Column;
    import javax.persistence.Entity;
    import javax.persistence.FetchType;
    import javax.persistence.GeneratedValue;
    import static javax.persistence.GenerationType.IDENTITY;
    import javax.persistence.Id;
    import javax.persistence.JoinColumn;
    import javax.persistence.ManyToOne;
    import javax.persistence.Table;
    import javax.persistence.Temporal;
    import javax.persistence.TemporalType;

    import com.fasterxml.jackson.annotation.JsonBackReference;
    import com.fasterxml.jackson.annotation.JsonIdentityInfo;
    import com.fasterxml.jackson.annotation.ObjectIdGenerators;

    /**
     * Address generated by hbm2java
     */
    @Entity
    @Table(name = "address", catalog = "testdb")
    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "addressId")
    public class Address implements java.io.Serializable {

        private Integer addressId;
        private AppUser appUser;
        private String text;
        private Date lastUpdatedDate;

        public Address() {
        }

        public Address(String text, Date lastUpdatedDate) {
            this.text = text;
            this.lastUpdatedDate = lastUpdatedDate;
        }

        public Address(AppUser appUser, String text, Date lastUpdatedDate) {
            this.appUser = appUser;
            this.text = text;
            this.lastUpdatedDate = lastUpdatedDate;
        }

        @Id
        @GeneratedValue(strategy = IDENTITY)

        @Column(name = "addressId", unique = true, nullable = false)
        public Integer getAddressId() {
            return this.addressId;
        }

        public void setAddressId(Integer addressId) {
            this.addressId = addressId;
        }

        @ManyToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
        @JoinColumn(name = "id")
        @JsonBackReference(value = "id-appUser")
        public AppUser getAppUser() {
            return this.appUser;
        }

        public void setAppUser(AppUser appUser) {
            this.appUser = appUser;
        }

        @Column(name = "text", nullable = false, length = 45)
        public String getText() {
            return this.text;
        }

        public void setText(String text) {
            this.text = text;
        }

        @Temporal(TemporalType.TIMESTAMP)
        @Column(name = "lastUpdatedDate", nullable = false, length = 19)
        public Date getLastUpdatedDate() {
            return this.lastUpdatedDate;
        }

        public void setLastUpdatedDate(Date lastUpdatedDate) {
            this.lastUpdatedDate = lastUpdatedDate;
        }

    }

我在github中上传了代码：https://github.com/harshalpatil2012/Springboot

Answer 1

您缺少父实体AppUser中地址属性的@JsonManagedReference注释，这就是用@JsonBackReference注释的子属性无法获取值的原因。

这两个注释，@JsonManaged引用和@JsonBack引用，用于处理此父子关系。