问题
@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;
...
}
When this Set is updated the existing activePolicyRules have their category_policy_id set to null in the database and new ones are inserted. I'd like for the original ones to be deleted.
I thought adding the orphanRemoval = true would do that but it's not. Other questions I've seen on this appear to have bi-directional relationships and setting the parent to null solves it, but this is not a bi-directional relationship.
Any suggestions?
Using Hibernate 3.5.3
Edit: This only happens when an existing AbstractPolicyRule exists in the database, I remove it from the list and then save the Category again. It's foreign key, category_policy_id, is set to null instead of being deleted.
[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
Also tried a join table since the Hibernate documentation discourages the previous way:
@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;
...
}
This has the same issue. The row in the mapping table is deleted but the AbstractPolicyRule still contains the removed item.
回答1:
I'm using orphanRemoval=true with an unidirectional One-to-Many association without any problem.
And actually, I tested your code and the following scenario (AbstractPolicyRule implementing equals/hashCode correctly):
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());
just works as expected. Below the generated traces:
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
The first policy rule gets deleted.
If this is not representative of what you're doing, you should maybe provide more code.
Update: Answering a comment from the OP...
Wow I just changed the saveOrUpdate call to merge and now it's removing appropriately. You have any insight why that is?
Just a guess: since orphanRemoval is a JPA thing, I wonder if saveOrUpdate will deal appropriately with it (actually, I thought you were using the EntityManager API since you mentioned JPA).
回答2:
First make sure your classes implement the hashCode() and equals() methods, so that hibernate knows that exactly these items are removed from the set.
Then try defining the hibernate @Cascade annotation, specifying the delete-orphan cascade type there and observer whether the same happens. If it works the way you want it - report a bug in hibernate and temporarily use the proprietary annotation. Otherwise - update the question with the details
来源：https://stackoverflow.com/questions/3304092/orphans-remain-in-database-even-with-orphanremoval-true-on-one-to-many-relations