与同一实体的多对多关系

Question

I have a User entity which can be a Manager or Client , Manager can have many Clients and Client can have many Managers .

I tried to map the User entity like this:

  @Id
  @GeneratedValue(strategy = AUTO)
  private UUID uuid;

  @ManyToMany
  @JoinTable(name = "managers_clients",
      joinColumns = {
          @JoinColumn(name = "clientUuid", referencedColumnName = "uuid", nullable = false)},
      inverseJoinColumns = {
          @JoinColumn(name = "managerUuid", referencedColumnName = "uuid", nullable = false)})
  private List<UserEntity> managers;


  @ManyToMany(mappedBy = "managers")
  private List<UserEntity> clients;

But unfortunately, I have an error:

failed to lazily initialize a collection of role: com.company.domain.common.entities.UserEntity.managers, could not initialize proxy - no Session

Can someone explain why this happening and how can I overcome this issue? Many thanks!

Answer 1

The problem is that you do not have a session during the fetching of the data. I'm not sure where you are fetching data, but try to add @Transactional to this method.

This will make sure the JPA uses a session to get the data.