Hibernate, bidirecctional updating

Question

I am trying to update records of Users with serveral Roles in 2 tables (User and UserRole) with hibernate. When I do the save it works properly, however, when I try to update, if the object contains a role that is stored in the database it fails. I didn't found a good answer but I guess it can't be done directly with the method "update", the bidirection should me implemented mannualy in the update isn't it?. I followed the structure of Spring Security for users.

This is my User class:

@Entity
@Table(name = "users", schema = "cmsdb")
public class User {

private String username;
private String password;
private boolean enabled;

private Set<UserRole> userRole = new HashSet<UserRole>(0);

public User() {
}

public User(String username, String password, boolean enabled) {
    this.username = username;
    this.password = password;
    this.enabled = enabled;
}

public User(String username, String password, 
    boolean enabled, Set<UserRole> userRole) {
    this.username = username;
    this.password = password;
    this.enabled = enabled;
    this.userRole = userRole;
}

@Id
@Column(name = "username", unique = true, nullable = false, length = 45)
public String getUsername() {
    return username;
}

public void setUsername(String username) {
    this.username = username;
}

@Column(name = "password", nullable = false, length = 60)
public String getPassword() {
    return password;
}

public void setPassword(String password) {
    this.password = password;
}

@Column(name = "enabled", nullable = false)
public boolean isEnabled() {
    return enabled;
}

public void setEnabled(boolean enabled) {
    this.enabled = enabled;
}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "user")  //,cascade = {CascadeType.ALL}
@Cascade({CascadeType.SAVE_UPDATE,CascadeType.DELETE})
@OnDelete(action = OnDeleteAction.CASCADE)
public Set<UserRole> getUserRole() {
    return userRole;
}

public void setUserRole(Set<UserRole> userRole) {
    this.userRole = userRole;
}
}

This is my UserRole class:

@Entity
@Table(name = "user_roles", schema = "cmsdb", 
uniqueConstraints = @UniqueConstraint(
    columnNames = { "role", "username" }))
public class UserRole {

private Integer userRoleId;
private User user;
@ValidRole
private String role;

public UserRole () {

}

public UserRole(User user, String role) {
    this.user = user;
    this.role = role;
}

@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "user_role_id", 
    unique = true, nullable = false)
public Integer getUserRoleId() {
    return userRoleId;
}

public void setUserRoleId(Integer userRoleId) {
    this.userRoleId = userRoleId;
}

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "username", nullable = false)
public User getUser() {
    return user;
}

public void setUser(User user) {
    this.user = user;
}

@Column(name = "role", nullable = false, length = 45)
public String getRole() {
    return role;
}

public void setRole(String role) {
    this.role = role;
}

public String toString () {
    return role;
}

@Override
public int hashCode() {
    return userRoleId;
}

@Override
public boolean equals(Object obj) {
    UserRole role = (UserRole) obj;
    return (userRoleId == role.getUserRoleId());
}
}

These are my DAO methods:

// IT WORKS PROPERLY
@Override
@Transactional
public boolean createUser(User user) {
    String hashedPassword = passwordEncoder.encode(user.getPassword());
    user.setPassword(hashedPassword);

    Set<UserRole> roles = new HashSet<UserRole> ();
    for(UserRole role: user.getUserRole()) {
        roles.add(new UserRole(user,role.getRole()));   
    }

    user.setUserRole(roles);
    sessionFactory.getCurrentSession().save(user);
    return true;
}

// It doesn't work if it tries to update an User with an UserRole stored in the UserRole table in the database
@Override
@Transactional
public boolean updateUser(User user) {

// Get user by id
    User userpersis = (User) getSessionFactory().getCurrentSession().load(User.class, user.getUsername());

  // Primary key shouldn't be modified
  userpersis.setEnabled(user.isEnabled());
  userpersis.getUserRole().retainAll( user.getUserRole() );
  userpersis.getUserRole().addAll( user.getUserRole() );
  sessionFactory.getCurrentSession().update(userpersis);
  return true;
}

The error is:

WARN : org.hibernate.engine.jdbc.spi.SqlExceptionHelper - SQL Error: 1062, SQLState: 23000
ERROR: org.hibernate.engine.jdbc.spi.SqlExceptionHelper - Duplicate entry  'ROLE_MAINTENANCE-asdf' for key 'uni_username_role'
WARN : org.hibernate.engine.jdbc.spi.SqlExceptionHelper - SQL Warning Code: 1062, SQLState: 23000 ...

Thanks in advance.

Answer 1

In User, add orphanRemoval to the cascading:

@Cascade(cascade={CascadeType.ALL}, orphanRemoval=true)
@OnDelete(action = OnDeleteAction.CASCADE)
public Set<UserRole> getUserRole() { ...

(see e.g. JPA 2.0 orphanRemoval=true VS on delete Cascade)

Then, instead of

Set<UserRole> roles = new HashSet<UserRole> ();
// Guess for roles, should be needed to load them also from the db
for(UserRole role : user.getUserRole()) {
    roles.add(new UserRole(userpersis,role.getRole())); 
}

userpersis.setUserRole(roles);

try

userpersis.getUserRole().clear(); // Let Hibernate know that we're really removing all the references

for(UserRole role : user.getUserRole()) {
    userpersis.getUserRole().add(new UserRole(userpersis,role.getRole())); 
}

Although in fact, you probably don't even want to delete all UserRoles and then insert all new data. You could also do something like

userpersis.getUserRole().retainAll( user.getUserRole() );
userpersis.getUserRole().addAll( user.getUserRole() );

This, however, requires that you implement equals() and hashCode() in UserRole.

Edit: Does of course not work when, as in your case, the user's role objects cannot be the same as the userpersis's because of the backreference to the owning object.