[英]After Hibernate migration from 4 to 5 OneToOne relationship causes ConstraintViolationException
[英]After Hibernate migration from 5 to 5.5 adding entities to collections causes ConstraintViolationException
我们有这样的代码(我简化了代码以使其更清晰):
@Entity
@Table(name="storages")
class Storage {
@OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinTable(name = "storage_items", joinColumns = @JoinColumn(name = "storage_id"), inverseJoinColumns = @JoinColumn(name = "item_id"))
private Set<Item> items;
void putItemToStorage(Session session) {
Item item = new Item();
item.setStorage(this);
session.save(item);
items.add(item);
}
}
@Entity
@Table(name="items")
class Item {
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "storage_id")
private Storage storage;
public void setStorage(Storage storage) {
this.storage = storage;
}
}
我们在事务中调用“putItemToStorage”,但在 hibernate 5.5 中它会导致以下错误,而在 hibernate 5 中,相同的代码就像一个魅力:
> javax.persistence.PersistenceException:
> org.hibernate.exception.ConstraintViolationException: could not execute statement
> ...
> caused by org.postgresql.util.PSQLException: ERROR: insert or update on table
> "storage_items" violates foreign key constraint
> "fkla3c4upmtw4myssb3bfg2svkj" Detail: Key (storage_id)=(164) is not
> present in table "items".
因此,hibernate 5 解决了对items表和storage_items表的插入并按预期工作(将这两个项目添加到items表并通过加入表storage_items将项目链接到相应的存储),但在 hibernate 5.5 中它不再起作用。 我在谷歌和文档上花了很多时间,但找不到更改的内容或我做错了什么。
我在其他地方遇到了类似的错误,我暂时解决了它,将对象的保存分开并将对象插入到 2 个单独的事务中(它有效,但绝对不是正确的解决方案),因此,如何正确修复它的任何帮助都是非常感谢。
您应该只在一侧(持有关系的一侧)定义映射,例如。 像这样:
@Entity
@Table(name="storages")
class Storage {
@OneToMany(mappedBy = "storage", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Set<Item> items;
void putItemToStorage() {
Item item = new Item();
item.setStorage(this);
items.add(item);
}
}
@Entity
@Table(name="items")
class Item {
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "storage_id", referencedColumnName = "id")
private Storage storage;
public void setStorage(Storage storage) {
this.storage = storage;
}
}
请注意,这种方法很可能会导致 2 个查询:
storage_id = null
Item
记录storage_id
设置为它应该是的值为了防止它调整字段storage
上的注释:
@Entity
@Table(name="items")
class Item {
@ManyToOne(optional = false)
@JoinColumn(name = "storage_id", referencedColumnName = "id", nullable = false, updatable = false)
private Storage storage;
}
您还可以考虑将orphanRemoval = true
添加到items
,以防您想删除数据库中的记录。
@Entity
@Table(name="storages")
class Storage {
@OneToMany(mappedBy = "storage", cascade = CascadeType.ALL, fetch = FetchType.LAZY, orphanRemoval = true)
private Set<Item> items;
}
您的代码应该如下所示:
// assumming within transaction context
var storage = // get from eg. EntityManager or JPA repository (in spring)
storage.putItemToStorage();
// There is no need to call EntityManager::persist or EntityManager::merge
// if you are withing transaction context
// and you are working with managed entity
// and have cascade = CascadeType.ALL
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