Spring boot SpringBoot级联类型所有vs合并和分离实体
我拥有以下实体:Spring boot SpringBoot级联类型所有vs合并和分离实体,spring-boot,jpa,Spring Boot,Jpa,我拥有以下实体: @Entity @Getter @Setter @NoArgsConstructor @RequiredArgsConstructor public class Link extends Auditable { @Id @GeneratedValue private Long id; @NonNull private String title; @NonNull private String url; @
@Entity
@Getter @Setter @NoArgsConstructor @RequiredArgsConstructor
public class Link extends Auditable {
@Id
@GeneratedValue
private Long id;
@NonNull
private String title;
@NonNull
private String url;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "link")
private List<Comment> comments = new ArrayList<>();
@Transient
@Setter(AccessLevel.NONE)
private String userAlias ;
public String getUserAlias() {
if(user == null)
return "";
return user.getAlias();
}
@ManyToOne
private User user;
public Long getUser() {
if(user == null)
return -1L;
return user.getId();
}
public void addComment(Comment c) {
comments.add(c);
c.setLink(this);
}
}
@Entity
@Getter @Setter @NoArgsConstructor @RequiredArgsConstructor
public class Comment extends Auditable{
@Id
@GeneratedValue
private Long id;
@NonNull
private String comment;
@ManyToOne(fetch = FetchType.LAZY)
private Link link;
public Long getLink() {
return link.getId();
}
}
但是,如果我先保存注释:
Link link = new Link("Getting started", "url");
Comment c = new Comment("Hello!");
commentRepository.save(c);
link.addComment(c);
linkRepository.save(link);
我明白了
Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on uk.me.dariosdesk.dariodemo.domain.Comment.link references an unknown entity: uk.me.dariosdesk.dariodemo.domain.Link
at org.hibernate.cfg.ToOneFkSecondPass.doSecondPass(ToOneFkSecondPass.java:97) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processEndOfQueue(InFlightMetadataCollectorImpl.java:1815) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processFkSecondPassesInOrder(InFlightMetadataCollectorImpl.java:1759) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.processSecondPasses(InFlightMetadataCollectorImpl.java:1646) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:287) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:903) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:934) ~[hibernate-core-5.4.0.Final.jar:5.4.0.Final]
将级联类型从ALL更改为MERGE似乎可以解决问题并接受这两种实现。(即:添加预先存在的注释或同时创建注释,然后通过链接保存)
1) 为什么会这样?
2) 在使用“合并”而不是“全部”时,有什么我应该注意的吗?存储库保存方法检查实体是否存在。对于新实体,调用persist;对于persistend,调用merge
@Transactional
public <S extends T> S save(S entity) {
if (entityInformation.isNew(entity)) {
em.persist(entity);
return entity;
} else {
return em.merge(entity);
}
}
@Transactional
公共存储(S实体){
if(entityInformation.isNew(实体)){
em.persist(实体);
返回实体;
}否则{
返回em.merge(实体);
}
}
在第二个用例中,链接是新实体,因此调用persist()。使用CascadeType.ALL persist()将级联到注释实体。注释已持久化,需要合并,persist()失败
如果使用CascadeType,则MERGE persist()不会级联到注释。它不会失败
@Transactional
public <S extends T> S save(S entity) {
if (entityInformation.isNew(entity)) {
em.persist(entity);
return entity;
} else {
return em.merge(entity);
}
}