java - 调用父持久方法时，JPA子对象不会持久

调用em.persist时，此子实体不会与父实体一起保留

@Entity
@Table(name="Z_PARENT")
public class Parent {

@Id
 @TableGenerator(name="parentIDGen", table="Z_JPA_ID_GEN",
 pkColumnName="ID_STRING", valueColumnName="ID_GEN",
 pkColumnValue="Z_PARENT")
 @GeneratedValue(strategy=GenerationType.TABLE, generator="parentIDGen")
private int id;

@Column(name="NAME")
private String name;


@OneToMany(mappedBy="parent",cascade={CascadeType.ALL})
Set<Child> children;

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;
}



@Override
public int hashCode() {
......
}

@Override
public boolean equals(Object obj) {
........
}

public Set<Child> getChildren() {
    return children;
}

public void setChildren(Set<Child> children) {
    this.children = children;
}

}

子表

@Entity
@Table(name="Z_CHILD")
public class Child {

@Id
@TableGenerator(name="childIDGen", table="Z_JPA_ID_GEN",
pkColumnName="ID_STRING", valueColumnName="ID_GEN",
pkColumnValue="Z_CHILD")
@GeneratedValue(strategy=GenerationType.TABLE,generator="childIDGen")
private int id;

@Column(name="NAME")
private String name;

@Column(name="PARENT_ID")
private int parentID;

@ManyToOne
@JoinColumn(name="PARENT_ID",referencedColumnName="ID")
private Parent parent;

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 getParentID() {
    return parentID;
}

public void setParentID(int parentID) {
    this.parentID = parentID;
}

@Override
public int hashCode() {
.....
}

@Override
public boolean equals(Object obj) {
.....
}

public Parent getParent() {
    return parent;
}

public void setParent(Parent parent) {
    this.parent = parent;
}

}

持久代码

 em.getTransaction().begin();
 Parent parent= new Parent();
 parent.setName("Parent1");
 Set<Child> children=new HashSet<Child>();
 Child child1=new Child();
 child1.setName("Child1");
 children.add(child1);
 parent.setChildren(children);
 em.persist(parent);
 em.getTransaction().commit();

openJPA生成的错误，我正在使用DB2


  引起原因：org.apache.openjpa.lib.jdbc.ReportingSQLException：DB2 SQL
  错误：SQLCODE = -530，SQLSTATE = 23503，
  SQLERRMC = ADMINISTRATOR.Z_CHILD.CC1369070983676，驱动程序= 3.58.81
  {prepstmnt 864433030插入Z_CHILD（ID，NAME，PARENT_ID）
      值（？，？，？）[params =（int）450，（String）Child1，（int）0]} [code = -530，state = 23503]
  org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.wrap（LoggingConnectionDecorator.java:281）
    在
  org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.wrap（LoggingConnectionDecorator.java:257）
    在
  org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator.access $ 1000（LoggingConnectionDecorator.java:72）
    在
  org.apache.openjpa.lib.jdbc.LoggingConnectionDecorator $ LoggingConnection $ LoggingPreparedStatement.executeUpdate（LoggingConnectionDecorator.java:1199）

最佳答案

SQL代码：-530
外键约束名称的插入或更新值无效

您必须了解，在持久化后阶段，在实体实例中设置了生成的ID。
JPA尚不能将生成的父ID传播给孩子。所以你必须自己设定

 em.getTransaction().begin();
 Parent parent= new Parent();
 parent.setName("Parent1");
 em.persist(parent); // here parent id is valuated
 Set<Child> children=new HashSet<Child>();
 Child child1=new Child();
 child1.setName("Child1");
 child1.setParentID(parent.getId());
 children.add(child1);
 parent.setChildren(children);
 em.merge(parent);
 em.getTransaction().commit();