How to get only one role from a set of roles

I’m trying to implement a simple spring security project where basically I have user and role entities. I have a set of roles “ADMIN” and “USER”.

Now I want to assign only “USER” role along with creating a new user.

I have tried to use List and collections with the same problem.

The User entity has Set<Role>

public class User {

    @Id
    @Column(name = "user_id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int user_id;

    @NotNull
    @Column(name = "user_name", unique = true)
    private String userName;

    @NotNull
    @Column(name = "first_name")
    private String firstName;

    @NotNull
    @Column(name = "last_name")
    private String lastName;

    @Column(name = "roles")
    @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    @JoinTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<Role> roles;}

And Role entity:

public class Role {

    }
    @Id
    private int role_id;
    private String role;

}

And here is the saveMyUser method to save the user to my database. When I use:

public void saveMyUser(User user) {
    Set<Role> hash_Set = new HashSet<Role>();
    user.setPassword(encoder().encode(user.getPassword()));
        user.setRoles(new HashSet<>(roleRepository.findAll())); <--- Here
        userRepository.save(user);
    }

user.setRoles(new HashSet<>(roleRepository.findAll())); assign all roles to the user, since I want for new user only assign the “USER” role.

I tried user.setRoles(new HashSet<>(roleRepository.findByRole(2))); and also I tried user.setRoles(new HashSet<>(roleRepository.findByID(2))); with this error: Cannot infer type arguments for HashSet<>.

Role table in my database:

role_id    role
1          ADMIN
2          USER

Answer

The HashSet constructor takes a Collection, not a single element. This line:

user.setRoles(new HashSet<>(roleRepository.findAll()));

creates a new HashSet with all of your roles. This line

user.setRoles(new HashSet<>(roleRepository.findByRole(2)));

tries to create a new HashSet with a single element in the constructor, which won’t work as a Role is not an instance of Collection.

Just fetch your role, create a HashSet, add the role and THEN set the user’s role:

Role role = roleRepository.findByRole(2);
Set<Role> roles = new HashSet<>();
roles.add(role);
user.setRoles(roles);