一个实体可以有多个多对多关系吗?

I have a table that has two different many-to-many relations to two different tables. Let's say I have User <---> UserRole <--> Role and User <--> UserGroups <--> Groups. Since I am new to hibernate and database mapping I was wondering if having my User entity have attributes roles and groups in it, both with @ManytoMany annotations is good practice and acceptable?

我有一个表，它有两个不同的多对多关系到两个不同的表。假设我有用户<--> UserRole <- >角色和用户<- > UserGroups <- >组。由于我是hibernate和数据库映射的新手，我想知道是否让我的用户实体在其中包含属性角色和组，使用@ManytoMany注释都是好的实践，可以接受吗?

i.e.:

例如:

 @Entity(name = "User")
 @Table(name = "USER")
 public class User {

 .... /* Obviously Id would go here and all other attributes */

 @ManyToMany(cascade = CascadeType.ALL)
 @JoinTable(name = "UserRole", joinColumns = { @JoinColumn(name="USER_ID") },
            inverseJoinColumns = { @JoinColumn(name = "ROLE_ID") } )
 private Set<Role> roles = new HashSet<Role>();

 @ManyToMany(cascade = CascadeType.ALL)
 @JoinTable(name = "UserGroup", joinColumns = { @JoinColumn(name="USER_ID") },
            inverseJoinColumns = { @JoinColumn(name = "GROUP_ID") } )
 private Set<Group> groups = new HashSet<Group>();

1 个解决方案

#1

Sure; lots of types have multiple many-to-many.

确定;很多类型都有多对多。

I think minimizing many-to-many relationships is a good idea, but it's a natural structure, and is found all over the place.

我认为最小化多对多关系是一个好主意，但它是一个自然结构，到处都可以找到。

#1