java – 非主键列上的Hibernate Cascaded update

2023年5月8日 262次阅读

我有两个表格,这样的结构.

>表格：

1)Obj表 –

2)subobj表

我的方案是我有is_deleted列,在删除时我不想删除记录而是我想将is_deleted设置为true并更新所需的依赖项.

>详细的scenrios：

1)考虑,用户正在从obj表中删除一行,该表具有Id 1.now subobj表与obj_id相关联的行1应将is_deleted设置为true.

2)subobj表包含一个自引用fk’parent_subobj’.在这种情况下,我也想管理依赖项,例如,如果用户正在删除具有id 2的subobj记录,那么对于具有“parent_subobj”2的记录,is_deleted应为true.

实体类:(使用JBOSS工具进行逆向工程)

Obj类： –

@Entity
@Table(name = "obj", schema = "public")
public class Obj implements java.io.Serializable
{
  private static final long serialVersionUID = 1L;

  @Id
  @Column(name = "id", unique = true, nullable = false)
  private int id;

  @Column(name = "obj_name", length = 100)
  private String objName;

  @Column(name = "is_deleted")
  private Boolean isDeleted;

  @OneToMany(fetch = FetchType.LAZY, mappedBy = "obj")
  private Set<Subobj> subobjs = new HashSet<Subobj>(0);
 // getters and setters
}

Subobj类： –

@Entity
@Table(name = "subobj", schema = "public")
public class Subobj implements java.io.Serializable
{
  @Id
  @Column(name = "id", unique = true, nullable = false)
  private int id;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "obj_id")
  private Obj obj;

  @ManyToOne(fetch = FetchType.LAZY)
  @JoinColumn(name = "parent_subobj")
  private Subobj subobj;

  @Column(name = "subobj_name", length = 100)
  private String subobjName;

  @Column(name = "is_deleted")
  private Boolean isDeleted;

  @OneToMany(fetch = FetchType.LAZY, mappedBy = "subobj")
  private Set<Subobj> subobjs = new HashSet<Subobj>(0);
}

所以可以在Hibernate中这样做,或者我必须为级联更新创建一个单独的触发器.请提出所需的更改建议

最佳答案 Hibernate和PostgreSQL仅支持“标准”级联操作,例如直接删除记录.没有您想要的那种“开箱即用”级联更新.您可以在java代码中编写您正在寻找的行为,但是将其作为两个触发器进行编写更清晰,更不容易出错(想象两个Java应用程序访问同一个表).

obj上的触发器功能和触发器：

CREATE FUNCTION del_obj() RETURNS trigger AS $$
BEGIN
  UPDATE obj SET is_deleted = true WHERE id = OLD.id;
  UPDATE subobj SET is_deleted = true WHERE obj_id = OLD.id;
  RETURN NULL; -- fail the delete operation
END; $$LANGUAGE plpgsql;

CREATE TRIGGER tr_del_obj
  BEFORE DELETE ON obj
  FOR EACH ROW EXECUTE PROCEDURE del_obj();

subobj上的触发器功能和触发器：

CREATE FUNCTION del_subobj() RETURNS trigger AS $$
BEGIN
  UPDATE subobj SET is_deleted = true WHERE id = OLD.id;
  DELETE FROM subobj WHERE parent_subobj = OLD.id;
  RETURN NULL; -- fail the delete operation
END; $$LANGUAGE plpgsql;

CREATE TRIGGER tr_del_subobj
  BEFORE DELETE ON subobj
  FOR EACH ROW EXECUTE PROCEDURE del_subobj();

仔细查看最后一个触发功能.它更新正在删除的记录的is_deleted列(但不是真的),然后删除引用它的记录.因此,当您“删除”id = 2的subobj记录时,该记录的is_deleted将设置为true,然后其他具有parent_subobj = 2的记录将被“删除”.这将级联更新字段is_deleted而不删除任何记录.但仔细考虑这里循环的可能性：如果你有一个id = 2的记录; parent_subobj = 3然后是另一个id = 3的记录; parent_subobj = 2你有一个无限循环.您可以通过仔细管理parent_subobj的分配或以其他方式使用检查循环的recursive CTE来避免这种情况.

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