即使在一对多关系上设置了 orphanRemoval=true ，孤儿仍保留在数据库中（JPA/Hibernate）

Question

@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@Table(name = "company_policies")
@DiscriminatorColumn(name = "rule_name")
public abstract class AbstractPolicyRule implements Serializable {

  @Transient
  private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue
  private Long id;
  private String value;

  ...
}

_

@Entity
public class Category implements Serializable {

  @Transient
  private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue
  private Long id;
  @Column(name = "category_name")
  private String name;

  @OneToMany(fetch = FetchType.EAGER, cascade = { CascadeType.ALL }, orphanRemoval = true)
  @JoinColumn(name = "category_policy_id", referencedColumnName = "id")
  private Set<AbstractPolicyRule> activePolicyRules;

  ...
}

当此集合更新时，现有的 activePolicyRules 在数据库中将其category_policy_id 设置为 null，并插入新的。我想把原来的删掉。

我认为添加 orphanRemoval = true 可以做到这一点，但事实并非如此。我在这方面看到的其他问题似乎具有双向关系，并将父项设置为 null 可以解决该问题，但这不是双向关系。

有什么建议吗？

使用 Hibernate 3.5.3

编辑： 仅当数据库中存在现有 AbstractPolicyRule 时才会发生这种情况，我将其从列表中删除，然后再次保存类别。它的外键category_policy_id 设置为null 而不是被删除。

[DEBUG] Collection found: [domain.category.Category.activePolicyRules#1], was: 
[<unreferenced>] (initialized)
[DEBUG] Flushed: 0 insertions, 2 updates, 0 deletions to 2 objects
[DEBUG] Flushed: 1 (re)creations, 0 updates, 1 removals to 1 collections
...
[DEBUG] Deleting collection: [domain.category.Category2.activePolicyRules#1]
[DEBUG] about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
[DEBUG] update company_policies set category_policy_id=null where category_policy_id=?
[DEBUG] done deleting collection

还尝试了连接表，因为 Hibernate 文档不鼓励以前的方式：

@Entity
public class Category implements Serializable {

  @Transient
  private static final long serialVersionUID = 1L;

  @Id
  @GeneratedValue
  private Long id;
  @Column(name = "category_name")
  private String name;

  @OneToMany(fetch = FetchType.EAGER, cascade = { CascadeType.ALL }, orphanRemoval = true)
  @JoinTable(name = "policy_rule_mapping", 
    joinColumns = @JoinColumn(name = "category_id"), 
    inverseJoinColumns = @JoinColumn(name = "rule_id"))
  private Set<AbstractPolicyRule> activePolicyRules;

  ...
}

这有同样的问题。映射表中的行已删除，但 AbstractPolicyRule 仍包含已删除的项目。

Answer 1

我使用 orphanRemoval=true 进行单向一对多关联，没有任何问题。

实际上，我测试了您的代码和以下场景（AbstractPolicyRule 正确实现 equals/hashCode）：

Category category = new Category();
AbstractPolicyRule policyRule1 = new AbstractPolicyRule("foo");

category.addToActivePolicyRules(policyRule1);
em.persist(category);
em.flush();

assertNotNull(category.getId());
assertNotNull(category.getActivePolicyRules());
assertEquals(1, category.getActivePolicyRules().size());

category.removeFromActivePolicyRules(policyRule1);
category.addToActivePolicyRules(new AbstractPolicyRule("bar"));
// category = em.merge(category); // works with or without
em.flush();
assertEquals(1, category.getActivePolicyRules().size());

按预期工作。在生成的跟踪下方：

22:54:30.817 [main] DEBUG org.hibernate.SQL - insert into Category (id, category_name) values (null, ?)
Hibernate: insert into Category (id, category_name) values (null, ?)
22:54:30.824 [main] TRACE org.hibernate.type.StringType - binding null to parameter: 1
22:54:30.844 [main] DEBUG o.h.id.IdentifierGeneratorHelper - Natively generated identity: 1
...
22:54:30.872 [main] DEBUG org.hibernate.SQL - insert into AbstractPolicyRule (id, name) values (null, ?)
Hibernate: insert into AbstractPolicyRule (id, name) values (null, ?)
22:54:30.873 [main] TRACE org.hibernate.type.StringType - binding 'foo' to parameter: 1
22:54:30.874 [main] DEBUG o.h.id.IdentifierGeneratorHelper - Natively generated identity: 1
...
22:54:30.924 [main] DEBUG org.hibernate.SQL - update AbstractPolicyRule set category_policy_id=? where id=?
Hibernate: update AbstractPolicyRule set category_policy_id=? where id=?
22:54:30.927 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 1
22:54:30.928 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 2
22:54:30.929 [main] DEBUG o.h.p.c.AbstractCollectionPersister - done inserting collection: 1 rows inserted
22:54:30.929 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - Executing batch size: 1
...
22:54:30.945 [main] DEBUG org.hibernate.SQL - insert into AbstractPolicyRule (id, name) values (null, ?)
Hibernate: insert into AbstractPolicyRule (id, name) values (null, ?)
22:54:30.948 [main] TRACE org.hibernate.type.StringType - binding 'bar' to parameter: 1
22:54:30.948 [main] DEBUG o.h.id.IdentifierGeneratorHelper - Natively generated identity: 2
...
22:54:30.990 [main] DEBUG org.hibernate.SQL - update AbstractPolicyRule set category_policy_id=null where category_policy_id=? and id=?
Hibernate: update AbstractPolicyRule set category_policy_id=null where category_policy_id=? and id=?
22:54:30.991 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 1
22:54:30.992 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 2
22:54:30.993 [main] DEBUG o.h.p.c.AbstractCollectionPersister - done deleting collection rows: 1 deleted
22:54:30.993 [main] DEBUG o.h.p.c.AbstractCollectionPersister - Inserting rows of collection: [com.stackoverflow.q3304092.Category.activePolicyRules#1]
22:54:30.994 [main] DEBUG org.hibernate.jdbc.AbstractBatcher - Executing batch size: 1
...
22:54:30.996 [main] DEBUG org.hibernate.SQL - update AbstractPolicyRule set category_policy_id=? where id=?
Hibernate: update AbstractPolicyRule set category_policy_id=? where id=?
22:54:30.997 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 1
22:54:30.998 [main] TRACE org.hibernate.type.LongType - binding '2' to parameter: 2
22:54:31.002 [main] DEBUG o.h.p.c.AbstractCollectionPersister - done inserting rows: 1 inserted
...
22:54:31.015 [main] DEBUG org.hibernate.SQL - delete from AbstractPolicyRule where id=?
Hibernate: delete from AbstractPolicyRule where id=?
22:54:31.017 [main] TRACE org.hibernate.type.LongType - binding '1' to parameter: 1

第一个策略规则被删除。

如果这不能代表您正在做的事情，您也许应该提供更多代码。

更新：回答OP的评论...

哇，我刚刚将 saveOrUpdate 调用更改为合并，现在它正在适当删除。您知道这是为什么吗？

只是猜测：由于 orphanRemoval 是 JPA 的东西，我想知道 saveOrUpdate 是否会适当地处理它（实际上，我以为你正在使用 EntityManager > API，因为您提到了 JPA）。

Answer 2

首先确保您的类实现了 hashCode() 和 equals() 方法，以便 hibernate 确切地知道这些项已从集合中删除。

然后尝试定义 hibernate @Cascade 注释，指定删除孤立级联类型并观察是否发生相同的情况。如果它按照您想要的方式工作 - 报告休眠中的错误并暂时使用专有注释。否则 - 用详细信息更新问题