新 Table 已创建，而不是更新现有的。一对多映射与复合键，弹簧启动，休眠

Question

我的架构中有两个 table，它们之间存在一对多关系。

单位和unit_bridge

单元有 2 列 id 和 name

unit_bridge 有两列，unit_master_id 和 unit_slave_id。两者一起组成一个复合键。这里unit_slave_id是id[=55=的外键] 单位列。

当我收到 POST 请求时，正在创建一个名为 unit_child_units[=55 的新 table =] 在数据库中。并且 unit_bridge 正在更新为 unit_slave_id 列的错误值。尽管 unit_master_id 的值在 unit_bridge table 中是正确的，但它对应的是 unit_slave_id 映射错了。

我不想要新的 table，而是想更新我的 unit_bridge table，因为我收到 POST用户请求单位 table.

这是我的 json 请求，

{ "name" : "john doe", "childUnits" : [ { "unitBridgeId" :{ "unit_master_id" : 4 } } ] }

这是我的模型。

Unit.java

import java.io.Serializable; import java.util.HashSet; import java.util.Set; import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.GenerationType; import javax.persistence.Id; import javax.persistence.OneToMany; import javax.persistence.Table; import javax.persistence.Transient; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.annotation.JsonInclude.Include; @Entity @Table(name="unit") @JsonInclude(Include.NON_NULL) public class Unit implements Serializable{ @Id @GeneratedValue(strategy = GenerationType.AUTO) private int id; private String name; @Transient private int parent_id; @OneToMany(cascade=CascadeType.ALL) @PrimaryKeyJoinColumn private Set<UnitBridge> childUnits = new HashSet<UnitBridge>(); public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getParent_id() { return parent_id; } public void setParent_id(int parent_id) { this.parent_id = parent_id; } public Set<UnitBridge> getChildUnits() { return childUnits; } public void setChildUnits(Set<UnitBridge> childUnits) { this.childUnits = childUnits; } @Override public String toString() { return "Unit [id=" + id + ", name=" + name + ", parent_id=" + parent_id + ", childUnits=" + childUnits + "]"; } }

UnitBridge.java

import java.io.Serializable; import javax.persistence.EmbeddedId; import javax.persistence.Entity; import javax.persistence.Table; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.annotation.JsonInclude.Include; @Entity @Table(name="unit_bridge") @JsonInclude(Include.NON_NULL) public class UnitBridge implements Serializable{ /** * */ private static final long serialVersionUID = 1L; @EmbeddedId private UnitBridgeId unitBridgeId; @Override public String toString() { return "UnitBridge [unitBridgeId=" + unitBridgeId + "]"; } public UnitBridgeId getUnitBridgeId() { return unitBridgeId; } public void setUnitBridgeId(UnitBridgeId unitBridgeId) { this.unitBridgeId = unitBridgeId; } public int getUnit_master_id() { return unitBridgeId.getUnit_master_id(); } public int getUnit_slave_id() { return unitBridgeId.getUnit_slave_id(); } public void setUnit_master_id(int unit_master_id) { unitBridgeId.setUnit_master_id(unit_master_id); } public void setUnit_slave_id(int unit_slave_id) { unitBridgeId.setUnit_slave_id(unit_slave_id); } }

UnitBridgeId.java

import java.io.Serializable; import javax.persistence.Embeddable; import com.fasterxml.jackson.annotation.JsonInclude; import com.fasterxml.jackson.annotation.JsonInclude.Include; @Embeddable public class UnitBridgeId implements Serializable { private static final long serialVersionUID = 1L; private int unit_master_id; private int unit_slave_id; public UnitBridgeId() { } public UnitBridgeId(int unit_master_id, int unit_slave_id) { this.unit_master_id = unit_master_id; this.unit_slave_id=unit_slave_id; } public int getUnit_master_id() { return unit_master_id; } public void setUnit_master_id(int unit_master_id) { this.unit_master_id = unit_master_id; } public int getUnit_slave_id() { return unit_slave_id; } public void setUnit_slave_id(int unit_slave_id) { this.unit_slave_id = unit_slave_id; } @Override public int hashCode() { final int prime = 31; int result = 1; result = prime * result + unit_master_id; result = prime * result + unit_slave_id; return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (obj == null) return false; if (getClass() != obj.getClass()) return false; UnitBridgeId other = (UnitBridgeId) obj; if (unit_master_id != other.unit_master_id) return false; if (unit_slave_id != other.unit_slave_id) return false; return true; } @Override public String toString() { return "UnitBridgeId [unit_master_id=" + unit_master_id + ", unit_slave_id=" + unit_slave_id + "]"; } }

Answer 1

我认为这是一个完美的例子，我们需要使用 @IdClass 注释，而不是 @Embeddable 作为组合键。

@Entity
@Table(name="unit")
public class Unit implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int id;
    private String name;

    @Transient
    private int parent_id;

    @OneToMany(mappedBy = "unit_slave_id", cascade = CascadeType.ALL)
    private Set<UnitBridge> childUnits = new HashSet<UnitBridge>();

    public int getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

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

    public int getParent_id() {
        return parent_id;
    }

    public void setParent_id(int parent_id) {
        this.parent_id = parent_id;
    }

    public Set<UnitBridge> getChildUnits() {
        return childUnits;
    }

    public void setChildUnits(Set<UnitBridge> childUnits) {
        this.childUnits = childUnits;
    }

    @Override
    public String toString() {
        return "Unit [id=" + id + ", name=" + name + ", parent_id=" + parent_id + "]";
    }


    public static void main(String[] args) {


        SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction transaction = session.beginTransaction();

        Unit unit = new Unit();
        unit.setName("A");

        session.save(unit);

        Set<UnitBridge> unitBridges = new HashSet<>();
        {
            UnitBridge unitBridge = new UnitBridge();
            unitBridge.setUnit_master_id(100);
            unitBridge.setUnit_slave_id(unit);
            unitBridges.add(unitBridge);
        }
        {
            UnitBridge unitBridge = new UnitBridge();
            unitBridge.setUnit_master_id(200);
            unitBridge.setUnit_slave_id(unit);
            unitBridges.add(unitBridge);
        }
        unit.setChildUnits(unitBridges);

        transaction.commit();

//        Unit unit = session.get(Unit.class,1);
//        System.out.println(unit.getId());
//        System.out.println(unit.getChildUnits().iterator().next().getUnit_master_id());

        session.close();
    }
}

@Entity
@Table(name="unit_bridge")
@IdClass(UnitBridgeId.class)
public class UnitBridge implements Serializable{
    private static final long serialVersionUID = 1L;

    @Id
    private int unit_master_id;

    @ManyToOne
    @Id
    private Unit unit_slave_id;

    public int getUnit_master_id() {
        return unit_master_id;
    }

    public void setUnit_master_id(int unit_master_id) {
        this.unit_master_id = unit_master_id;
    }

    public Unit getUnit_slave_id() {
        return unit_slave_id;
    }

    public void setUnit_slave_id(Unit unit_slave_id) {
        this.unit_slave_id = unit_slave_id;
    }
}

public class UnitBridgeId implements Serializable {
    private static final long serialVersionUID = 1L;

    private int unit_master_id;

    private Unit unit_slave_id;

    public UnitBridgeId(){

    }
    public UnitBridgeId(int unit_master_id, Unit unit_slave_id) {
        this.unit_master_id = unit_master_id;
        this.unit_slave_id = unit_slave_id;
    }

    public int getUnit_master_id() {
        return unit_master_id;
    }

    public void setUnit_master_id(int unit_master_id) {
        this.unit_master_id = unit_master_id;
    }

    public Unit getUnit_slave_id() {
        return unit_slave_id;
    }

    public void setUnit_slave_id(Unit unit_slave_id) {
        this.unit_slave_id = unit_slave_id;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        UnitBridgeId that = (UnitBridgeId) o;
        return unit_master_id == that.unit_master_id &&
                Objects.equals(unit_slave_id, that.unit_slave_id);
    }

    @Override
    public int hashCode() {
        return Objects.hash(unit_master_id, unit_slave_id);
    }

    @Override
    public String toString() {
        return "UnitBridgeId [unit_master_id=" + unit_master_id + ", unit_slave_id=" + unit_slave_id + "]";
    }

}

Hibernate 创建的表

Hibernate: create table unit (id integer not null, name varchar(255), primary key (id)) engine=MyISAM
Hibernate: create table unit_bridge (unit_master_id integer not null, unit_slave_id_id integer not null, primary key (unit_master_id, unit_slave_id_id)) engine=MyISAM
Hibernate: alter table unit_bridge add constraint FKgv4psic91eix7b780lekkrdg4 foreign key (unit_slave_id_id) references unit (id)

单位table

unit_bridge table

新 Table 已创建，而不是更新现有的。一对多映射与复合键，弹簧启动，休眠

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