Spring updating many to many reletionship Issue

I'm trying to update my entity many to many by this json: as you can see i have this relation: Utente-Ruoli, Ruoli-Privileggi

I sending a list of id for ruoli and an id for user in the json DTO

this is the method in my Utente JPA:

  @Modifying(flushAutomatically = true, clearAutomatically = true)
    @Transactional
    @Query("UPDATE Utente u SET u.roles = :roles WHERE u.id = :userId")
    int saveUserRoles(@Param("userId") Integer userId, @Param("roles") Set<Ruoli> roles);

and this is where i perfom the service:

 public Utente addRolesToUser(RuoliDTO ruoliDTO) {
    log.info("{}.addRolesToUser adding user: {} to list roles: {}", this.getClass().getName(), ruoliDTO.getUser().getUsername(), ruoliDTO.getRoles().size());
    Utente utente = ruoliDTO.getUser();
    Set<Ruoli> rolesToAdd = ruoliDTO.getRoles();
    utente.setRoles(ruoliDTO.getRoles());
     userRepository.saveUserRoles(utente.getId(), rolesToAdd);
     return utente;
}

And i get always this error:

Parameter value [Ruoli{id=2, roleName='ADMIN', description='admin', privileggi=[Privileggi{id=1, privName='UNICACON_MDJS_USER', description='basic user', active=false}, Privileggi{id=3, privName='UNICACON_MDJS_ADMIN', description='admin role', active=true}, Privileggi{id=4, privName='ARCHICON_MDJS_USER', description='archicon role', active=true}]}] did not match expected type [java.util.Set (n/a)]; nested exception is java.lang.IllegalArgumentException: Parameter value [Ruoli{id=2, roleName='ADMIN', description='admin', privileggi=[Privileggi{id=1, privName='UNICACON_MDJS_USER', description='basic user', active=false}, Privileggi{id=3, privName='UNICACON_MDJS_ADMIN', description='admin role', active=true}, Privileggi{id=4, privName='ARCHICON_MDJS_USER', description='archicon role', active=true}]}] did not match expected type [java.util.Set (n/a)]

These are my entities:

     @Entity
    @Table(name = "utente")
@Data
    public class Utente implements Serializable {
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;
    
        @JsonIgnoreProperties("utenti")
        @ManyToMany(fetch = FetchType.EAGER, cascade = {CascadeType.MERGE, CascadeType.PERSIST})
        @JoinTable(
                name = "utente_ruolo",
                joinColumns = @JoinColumn(name = "utente_id", referencedColumnName = "id"),
                inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id")
        )
        private List<Ruoli> roles;
    }



 @Data
    @Entity
    @Table(name = "ruoli")
    public class Ruoli implements Serializable {
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;
    
        @JsonIgnore
        @ManyToMany(cascade ={ CascadeType.MERGE, CascadeType.PERSIST})
        @JoinTable(
                name = "utente_ruolo",
                joinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id"),
                inverseJoinColumns = @JoinColumn(name = "utente_id", referencedColumnName = "id")
        )
        private List<Utente> utenti;
    }

    @Entity
    @Data
    @Table(name = "privileggi")
    public class Privileggi implements Serializable {
    
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private Integer id;
    
        @Column(name = "priv_name")
        private String privName;
    
        @Column(name = "description")
        private String description;
    
        @Column(name = "active")
        private Boolean active;
    
        @JsonIgnore
        @ManyToMany( cascade ={ CascadeType.MERGE, CascadeType.PERSIST})
        @JoinTable(
                name = "ruolo_privileggi",
                joinColumns = @JoinColumn(name = "priv_id", referencedColumnName = "id"),
                inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id")
        )
        private List<Ruoli> ruoli;
    }

What Am I doing wrong?

Solution

Here is the answer shown below

First, you need to fetch the Utente entity from the database.
Then, you can update the Utente entity's roles with the roles from the RuoliDTO.

Finally, you can save the updated Utente entity back to the database.

 public Utente addRolesToUser(RuoliDTO ruoliDTO) {
     log.info("{}.addRolesToUser adding user: {} to list roles: {}", this.getClass().getName(), ruoliDTO.getUser().getUsername(), ruoliDTO.getRoles().size());

     // 1. Fetch the Utente entity from the database.
     Utente utente = userRepository.findById(ruoliDTO.getUser().getId()).orElse(null);

     if (utente != null) {
         // 2. Update the Utente entity's roles with the roles from RuoliDTO.
         utente.setRoles(ruoliDTO.getRoles());

         // 3. Save the updated Utente entity back to the database.
         utente = userRepository.save(utente);
     }

     return utente;
 }