LazyInitializationException when using @Inheritance

Question

I'm trying to use Inheritance using this project https://github.com/Baeldung/spring-security-registration.

This is my User:

@Data
@Entity
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(discriminatorType = DiscriminatorType.STRING, name = "TYPE")
public abstract class User {
     @ManyToMany(fetch = FetchType.EAGER)
     @JoinTable(name = "users_roles",joinColumns = @JoinColumn(name = "user_id", referencedColumnName = "id"),inverseJoinColumns = @JoinColumn(name = "role_id", referencedColumnName = "id"))
     private Collection<Role> roles;
}

and some subclass like UserAdmin:

@Entity
@DiscriminatorValue("ADMIN")
public class UserAdmin extends User {}

Then my role class is like this:

@Data
@Entity
public class Role {
     @ManyToMany(mappedBy = "roles")
     private Collection<User> users;
}

But I got this error when I register a user:

o.h.LazyInitializationException: failed to lazily initialize a collection of role: com.baeldung.persistence.model.Role.users, could not initialize proxy - no Session

Need help guys.

when you do many-to-many relations, they has to evaluate lazily since you cannot add 2 cycling data at the same time. check your code to see where you miss this requirements — Yılmaz Durmaz
– Yılmaz Durmaz, Commented Jan 17, 2022 at 10:42

ouflak · Accepted Answer · 2022-01-15 13:39:52Z

1

We need a bit more context, but you generally have two options:

Have the method where you call "getRoles()" be annotated with @Transactional.

or

Create a method in jpa with a @Query("SELECT u from user u join fetch u.roles where u.id =:id").

edited Jan 15, 2022 at 13:39

ouflak

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answered Jan 15, 2022 at 11:57

Petru-Cristian Boza

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4 Comments

Nantenaina Over a year ago

Thanks for your reply. I've just download the project and introduced UserAdmin and UserStaff. Got error when calling RegistrationController#confirmRegistration

Nantenaina Over a year ago

I have add annotation to RegistrationController#authWithoutPassword but still got error

Petru-Cristian Boza Over a year ago

I just noticed that the project is a bit more complex, I think it should still work if you were to add @Transactional on RegistrationController#confirmRegistration. But that is kinda a bad practice

Nantenaina Over a year ago

indeed, not a good practice adding this annotation.

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