[英]Mapping a list of Java 8 month enum in Hibernate
is it possible to map a list of java.time.Month to a seperate Table like so: 是否可以像这样将java.time.Month列表映射到单独的Table:
|MyEntity | |MyEntity_Month | |Month |
|---------------------| |------------------| |---------------|
|id : long | |myEntity_Id : long| |id : long |
| |----|month_Id : long |----| |
|---------------------| |------------------| |---------------|
I have tried it like this but it that only creates a table MyEntity_Month with a myEntity_Id and values: 我已经尝试过了,但是它只能创建一个带有myEntity_Id和值的表MyEntity_Month:
@ElementCollection(targetClass = Month.class, fetch = FetchType.EAGER)
@Enumerated(EnumType.STRING)
@CollectionTable(name = "MyEntity_Months"
, joinColumns = @JoinColumn(name = "myEntity_id"))
private List<Month> months;
The problem with that solution is that the values are repeated for each MyEntity instead of associated. 该解决方案的问题在于,对每个MyEntity重复这些值,而不是将其关联。 Database view of the above annotation configuration:
以上注释配置的数据库视图:
|MyEntity | |MyEntity_Month |
|---------------------| |-----------------------|
|id : long | |myEntity_id | MONTH |
|... |----|-----------------------|
|---------------------| |1 | NOVEMBER |
|1 | DECEMBER |
|2 | JANUARY |
|2 | DECEMBER |
|-----------------------|
Is it possible to map via assocation table so that I need only 12 Month Strings in the database? 是否可以通过关联表进行映射,以便数据库中仅需要12个月的字符串? I'm using Hibernate 4.3 / JPA 2.1 btw
我正在使用Hibernate 4.3 / JPA 2.1 btw
The type java.time.Month does not have @Entity annotations, so this is not recognized as an entity by hibernate. 类型java.time.Month没有@Entity批注,因此休眠不将其识别为实体。 You can achieve your desired table mapping if you introduce something like a MonthWrapper:
如果引入类似MonthWrapper的内容,则可以实现所需的表映射:
@Entity
public class MyEntity {
@Id
private Long id;
@OneToMany(fetch = FetchType.EAGER)
private List<MonthWrapper> months;
}
@Entity
public class MonthWrapper {
@Id
private Long id;
@Enumerated(EnumType.STRING)
private Month month;
}
Then if you run this through hibernate with a create-drop
hbm2ddl.auto
property, then you get the following tables: 然后,如果您使用
create-drop
hbm2ddl.auto
属性在休眠状态下运行此hbm2ddl.auto
,则会得到下表:
Hibernate: create table MonthWrapper (id bigint not null, month varchar(255), primary key (id))
休眠:创建表MonthWrapper(id bigint不为null,month varchar(255),主键(id))
Hibernate: create table MyEntity (id bigint not null, primary key (id))
休眠:创建表MyEntity(ID bigint不为null,主键(id))
Hibernate: create table MyEntity_MonthWrapper (MyEntity_id bigint not null, months_id bigint not null)
休眠:创建表MyEntity_MonthWrapper(MyEntity_id bigint不为空,months_id bigint不为空)
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