在服务 class 中创建方法以从 Spring 引导中的存储库获取数据

Question

我正在尝试创建一个返回特定角色的所有用户列表的方法。 我在服务 class 中有不同的方法，例如 findUserByName 等，但是当我尝试使用角色属性查找用户列表时它不起作用。 我确实在用户 model 中定义了角色。

用户 model：

@Table(name = "users")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "user_id")
    private Integer id;
    @Column(name = "user_name")
    @Length(min = 5, message = "*Your user name must have at least 5 characters")
    @NotEmpty(message = "*Please provide a user name")
    private String userName;
    @Column(name = "email")
    @Email(message = "*Please provide a valid Email")
    @NotEmpty(message = "*Please provide an email")
    private String email;
    @Column(name = "password")
    @Length(min = 5, message = "*Your password must have at least 5 characters")
    @NotEmpty(message = "*Please provide your password")
    private String password;
    @Column(name = "first_name")
    @NotEmpty(message = "*Please provide your name")
    private String firstName;
    @Column(name = "last_name")
    @NotEmpty(message = "*Please provide your last name")
    private String lastName;
    @Column(name = "active")
    private Boolean active;
    @ManyToMany(cascade = CascadeType.MERGE)
    @JoinTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<Role> roles;

}

角色 model：

@Table(name = "roles")
public class Role {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "role_id")
    private int id;
    @Column(name = "role")
    private String role;
}

用户服务：

@Service
public class UserService {

    private UserRepository userRepository;
    private RoleRepository roleRepository;
    private BCryptPasswordEncoder bCryptPasswordEncoder;

    @Autowired
    public UserService(UserRepository userRepository,
                       RoleRepository roleRepository,
                       BCryptPasswordEncoder bCryptPasswordEncoder) {
        this.userRepository = userRepository;
        this.roleRepository = roleRepository;
        this.bCryptPasswordEncoder = bCryptPasswordEncoder;
    }

    public User findUserByEmail(String email) {
        return userRepository.findByEmail(email);
    }

    public User findUserByUserName(String userName) {
        return userRepository.findByUserName(userName);
    }

    //method to find user by role
    public List<User> findUsersByRole() {
        return ;
    }


    public User saveUser(User user, String role) {
        user.setPassword(bCryptPasswordEncoder.encode(user.getPassword()));
        user.setActive(true);
        Role userRole = roleRepository.findByRole(role);
        user.setRoles(new HashSet<Role>(Arrays.asList(userRole)));
        return userRepository.save(user);
    }

}

角色存储库：

@Repository
public interface RoleRepository extends JpaRepository<Role, Integer> {
    Role findByRole(String role);

}

用户存储库：

@Repository
public interface UserRepository extends JpaRepository<User, Long> {
    User findByEmail(String email);
    User findByUserName(String userName);
}

Answer 1

您需要在UserRepository中编写查询以使用 ManyToMany User-Role 关联：

List<User> findByRolesId(Long id);  // using here ID of the role