情况
我有一个RoleEntity
和一个UserEntity
。 RoleEntity
包含UserEntity
列表,反之亦然,导致Many-To-Many
关系。
我的UserEntity
:
public class UserEntity implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(unique = true, nullable = false)
private String username;
@Column(name = "first_name", nullable = false)
private String firstName;
@Column(name = "last_name", nullable = false)
private String lastName;
@Column(nullable = false)
private String email;
@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.REFRESH)
@JoinTable(name = "uas_user_role",
joinColumns = @JoinColumn(name = "uas_user_id", referencedColumnName = "id"),
inverseJoinColumns = @JoinColumn(name = "uas_role_id", referencedColumnName = "id"),
uniqueConstraints = {
@UniqueConstraint(columnNames = {"uas_user_id", "uas_role_id"})}
)
private Set<RoleEntity> roles = new HashSet<>();
...
}
我的RoleEntity
:
public class RoleEntity implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@Column(unique = true, nullable = false)
private String name;
@ManyToMany(mappedBy = "roles")
private Set<UserEntity> users;
@ManyToMany
@JoinTable(
name = "uas_role_permission",
joinColumns
= @JoinColumn(name = "uas_role_id", referencedColumnName = "id"),
inverseJoinColumns
= @JoinColumn(name = "uas_permission_id", referencedColumnName = "id"),
uniqueConstraints = {
@UniqueConstraint(columnNames = {"uas_role_id", "uas_permission_id"})}
)
private Set<PermissionEntity> permissions;
...
}
目标
现在我想通过简单地更新单个实体来更改映射。例如,我想将UserEntity
添加到id = 1的RoleEntity
:
{
"id": 1,
"name": "Admin_Role",
"users": [{"id": 1}
]
}
将此RoleEntity
保存到它的角色存储库(JPARepository.saveAndFlush(Serializable)
),成功解析隐含的UserEntity
并返回更新的RoleEntity
{
"id": 1,
"name": "Admin_Role",
"users": [{
"id": 1,
"username": "admin",
"firstName": "Administrator",
"lastName": "Administrator",
"email": "[email protected]",
}
]
}
问题
我的测试全部通过,因为我只检查了save命令的返回值。现在我发现在坚持使用roleRepository.findOne(1)
之后,我将收到以下RoleEntity
:
{
"id": 1,
"name": "Admin_Role",
"users": []
}
UserEntity
映射没有得到持久化。同样在设置spring.jpa.show-sql=true
时,我发现在SELECT
命令期间只执行saveAndFlush
操作。我只想创建映射,并且不希望允许编辑映射实体,这就是我禁用任何级联的原因。
我期望通过这种方法,可以创建映射。我究竟做错了什么?
解
正如Amer Qarabsa所提到的:要创建双向映射,需要在两端进行设置。保存实体后添加一行已经成功了:
@Transactional
public RoleDto updateRole(RoleDto role) {
RoleEntity roleEntity = roleRepository.findOne(role.getId());
if (roleEntity==null){
throw new ResourceNotFoundException();
}
final RoleEntity savedRoleEntity = roleRepository.saveAndFlush(roleEntity);
savedRoleEntity.getUsers().forEach(user -> user.getRoles().add(savedRoleEntity));
return savedRoleEntity;
}
随着.saveAndFlush(roleEntity)
我将首先更新RoleEntity
并让JPA解决UserEntity
。在此之后,我只需将RoleEntity
设置为该角色的每个UserEntity
。在我的情况下,我不需要手动持久化,因为事务将负责持久保存任何未保存的更改。
那么在双向关系中它不是很简单,你不能把json和它映射到实体这么简单,关系的每一边都应该引用另一边,所以在你的情况下你需要把每个userentity里面角色实体并设置它的角色实体然后保存。