Spring data jpa projection repeats output when there is a manytomany annotation

Question

I have a user class related to a authority class with a manyToMany relationship between them.

I am using a projection to retrieve a list of users without some fields. There is a problem when I retrieve the list of authorities the user has, for each authority spring returns me the same object twice.

User class

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


@Id
@Column(name = "ID")
@GeneratedValue(strategy = GenerationType.AUTO, generator = "user_seq")
@SequenceGenerator(name = "user_seq", sequenceName = "user_seq", allocationSize = 1)
private Long id;

@Column(name = "apiKey", updatable = false, nullable = false, unique=true, columnDefinition = "BINARY(16)")    
private UUID apiKey;


@Column(name = "USERNAME", length = 50, unique = true)
@NotNull
@Size(min = 4, max = 50)
private String username;

@Column(name = "PASSWORD", length = 100)
@NotNull
@Size(min = 4, max = 100)
private String password;

@Column(name = "FIRSTNAME", length = 50)
@NotNull
@Size(min = 4, max = 50)
private String firstname;

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(
        name = "USER_AUTHORITY",
        joinColumns = {@JoinColumn(name = "USER_ID", referencedColumnName = "ID")},
        inverseJoinColumns = {@JoinColumn(name = "AUTHORITY_ID", referencedColumnName = "ID")})
private List<Authority> authorities;


}

User repository

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    User findByUsername(String username);

    List<UserWithUuid> findAllByNodeId(Long nodeId);  

    interface UserWithUuid {
        String getFirstname();
        String getLastname();       
        String getEmail();
        List<Authority> getAuthorities();
        UUID getApiKey();
    }



}

As you can see in the output it returns twice the same user but with a different role.

Output

[
    {
        "firstname": "daniel",
        "lastname": "mancera",
        "email": "daniel.mancera@dmance.eu",
        "apiKey": "7961609f-79d4-4ef2-9baa-6809978c038b",
        "authorities": [
            {
                "id": 1,
                "name": "ROLE_USER"
            }
        ]
    },
    {
        "firstname": "daniel",
        "lastname": "mancera",
        "email": "daniel.mancera@dmance.eu",
        "apiKey": "7961609f-79d4-4ef2-9baa-6809978c038b",
        "authorities": [
            {
                "id": 2,
                "name": "ROLE_MANAGER"
            }
        ]
    },
    {
        "firstname": "Roger",
        "lastname": "Rabbit",
        "email": "roger.rabiit@rab.it",
        "apiKey": "023bf60b-e79b-461f-bd30-65a920fe99e4",
        "authorities": [
            {
                "id": 1,
                "name": "ROLE_USER"
            }
        ]
    }
]

score 1 · Accepted Answer · answered Jan 30 '18 at 07:04

1

This is most likely this Bug https://jira.spring.io/browse/DATAJPA-1173

It is fixed in the current versions of Spring Data so upgrading the version you use should fix the issue.

answered Jan 30 '18 at 07:04

Jens Schauder

77,657
34
181
348

Thank you. I am a bit newbie at moment and I did not understand some topics when I was looking for an answer ;) – dmance Jan 30 '18 at 08:05
Everything is good. The question is easy to understand and issues are sometimes hard to find. Even took me two attempts although I knew it was there since I fixed it. – Jens Schauder Jan 30 '18 at 08:10
1

@Jens When we try to optimize the query methods with `@EntityGraph` annotation or with `join fetch` in the query, we still get duplicate parent entities. Regardless of whether they are entities or projections. Please check my [demo](https://github.com/Cepr0/duplicate-parent-entities)... – Cepr0 Jan 30 '18 at 22:09
@Cepr0 If you think this is a bug, please create a ticket. Otherwise, create a new SO question. – Jens Schauder Jan 31 '18 at 05:36
@Cepr0 Perhaps it is due to https://stackoverflow.com/questions/1995080/hibernate-criteria-returns-children-multiple-times-with-fetchtype-eager – user2829759 Apr 23 '18 at 17:22

Spring data jpa projection repeats output when there is a manytomany annotation

1 Answers1