[英]Persisting @OneToMany relations with @JoinColumn and @MapKeyColumn
I have two entities: 我有两个实体:
@Entity
Article {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
@OneToMany(fetch = FetchType.EAGER, cascade=CascadeType.ALL)
@JoinColumn(name="embed_id", referencedColumnName="id")
@MapKeyColumn(name = "language")
@MapKeyEnumerated(EnumType.ORDINAL)
private Map<Language, Locale> locales;
Article() {
locales.put(Language.CS, new Locale());
locales.put(Language.EN, new Locale());
}
}
@Entity
Locale {
@Id
private Long embed_id;
@Id
private Language language;
@Column(length = 256)
private String name;
}
Thanks to the constructor, I can make sure, that once an Article
is instantiated, two Locales
(with CascadeType.ALL) are associated with it. 感谢构造函数,我可以确保,一旦实例化了一个
Article
就会将两个Locales
(与CascadeType.ALL)相关联。
The problem comes when I try to persist such entity - I am getting: 当我试图坚持这样的实体时,问题出现了 - 我得到了:
javax.persistence.EntityExistsException:
a different object with the same identifier value was already associated
with the session: org...Locale#org...Locale@2bfdsc64
The problem is that neither embed_id
, nor language
have assigned values from the Article when persisting and Hibernate does not associate them after persisting Article. 问题是
embed_id
和language
都没有在持久化时从文章中赋值,而Hibernate在持久化文章后没有关联它们。 How can this be done? 如何才能做到这一点?
Edit 1: 编辑1:
I checked that when the embed_id
and language
are set manually, everything works correctly. 我检查过,当手动设置
embed_id
和language
,一切正常。 I just need to tell Hibernate, to set the value of @ JoinColumn
and @ MapKeyColumn
according to the @ OneToMany
relation. 我只需要告诉Hibernate,根据@
OneToMany
关系设置@ JoinColumn
和MapKeyColumn
的值。
Edit 2: 编辑2:
The problem with MapKeyColumn has an easy solution: MapKeyColumn的问题有一个简单的解决方案:
public void addLocale(Language l, Locale locale) {
locale.setLanguage(l);
this.locales.put(l);
}
But I am still unable to tell hibernate to associate the Locale.embed_id from Article.id. 但我仍然无法告诉hibernate将Article.id与Locale.embed_id相关联。
Edit 3: 编辑3:
I can see that the ID of article is properly generated, but then it is not put in the locale: 我可以看到文章的ID是正确生成的,但是它没有放在语言环境中:
DEBUG org.hibernate.event.internal.AbstractSaveEventListener -
Generated identifier: 87, using strategy: org.hibernate.id.SequenceGenerator
DEBUG org.hibernate.event.internal.AbstractSaveEventListener -
Generated identifier: component[language,embedId]{language=0, embedId=null}, using strategy: org.hibernate.id.CompositeNestedGeneratedValueGenerator
DEBUG org.hibernate.event.internal.AbstractSaveEventListener -
Generated identifier: component[language,embedId]{language=1, embedId=null}, using strategy: org.hibernate.id.CompositeNestedGeneratedValueGenerator
I guess the problem is, that you want to persist two empty locales. 我想问题是,你想要坚持两个空的语言环境。 And because you don't use a generator for the id-fields, the locales have the same (empty) primary key and therefore can't be persisted.
并且因为您没有为id字段使用生成器,所以语言环境具有相同的(空)主键,因此无法持久化。
I finally found the anwswer! 我终于找到了anwswer! The trick was to create Setter on Article and add Access to id as follows:
诀窍是在文章上创建Setter并添加对id的访问,如下所示:
@Id
@Getter
@Access(AccessType.PROPERTY)
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
public void setId(Long id) {
this.id = id;
this.getLocale(Language.CS).setEmbedId(id);
this.getLocale(Language.EN).setEmbedId(id);
}
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