Spring Boot JPA - OneToMany relationship causes infinite loop

Question

I have a two objects with simple @OneToMany relationship which looks as follows:

parent:

@Entity
public class ParentAccount {

  @Id
  @GeneratedValue
  private long id;
  private String name;

  @OneToMany(fetch = FetchType.EAGER, mappedBy = "parentAccount")
  private Set<LinkedAccount> linkedAccounts;

}

child:

@Entity
public class LinkedAccount {

  @Id
  @GeneratedValue
  private long id;

  @ManyToOne(optional = false)
  private ParentAccount parentAccount;

  private String name;

  // empty constructor for JPA
  public LinkedAccount() {
  }

}

I ma using Spring CrudRepository to operate with these entities. However, when calling ParentAccount parent = parentAccountRepository.findOne(id);, some kind of infinite loop starts happening and hibernate spams this all over the console:

Hibernate: select linkedacco0_.parent_account_id as parent_a6_1_0_, linkedacco0_.id as id1_0_0_, linkedacco0_.id as id1_0_1_, linkedacco0_.aws_id as aws_id2_0_1_, linkedacco0_.key_id as key_id3_0_1_, linkedacco0_.name as name4_0_1_, linkedacco0_.parent_account_id as parent_a6_0_1_, linkedacco0_.secret_key as secret_k5_0_1_ from linked_account linkedacco0_ where linkedacco0_.parent_account_id=?

I tried changed the fetch type to LAZY but then I get this error:

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.berrycloud.scheduler.model.ParentAccount.linkedAccounts, could not initialize proxy - no Session

(It seems that it is trying to do the lazy load outside of the transactional context).

This is my CRUD repository:

@Repository
public interface ParentAccountRepository extends CrudRepository<ParentAccount, Long> {
}

Could someone tell me how to resolve this issue? I would prefer the solution with EAGER fetch. Thank you for any tips

EDIT: here is the schema I am using

CREATE TABLE parent_account (
    id BIGINT auto_increment,
    name VARCHAR(80) null,
    PRIMARY KEY (`id`)
);

CREATE TABLE linked_account (
    id BIGINT auto_increment,
    parent_account_id BIGINT,
    name VARCHAR(80) null,
    FOREIGN KEY (`parent_account_id`) REFERENCES `parent_account` (`id`),
    PRIMARY KEY (`id`)
);

Solution 1

Problem solved. I was using a custom @toString method in the LinkedAccount which was referencing the ParentAccount. I had no idea that this could cause any problem and therefor I did not include the toString in my question.

Apparently, this was causing an infinite loop of lazy loading and removing this reference fixed the problem.

Solution 2

As the first answer suggests:

Do not use Lombok's @Data annotation on @Entity classes.

Reason: @Data generates hashcode(), equals() and toString() methods that use the generated getters. Using the getter means of course fetching new data even if the property was marked with FetchType=LAZY.

Somewhere along the way hibernate tries to log the data with toString() and it crashes.

Comments

[Smajl]

I would have to edit my sql schema (which already exists) to add the manager_id column. Also, spring has its way of doing this automatically so I would like to use the deafault Spring JPA way of resolving this issue

[Mejmo]

What is non spring jpa there? By the way, your code works for me, you have something in your database data wrong. Check it twice.

[Smajl]

I edited my question and added the schema I am using. Maybe there is something wrong with that?

[Smajl]

Also: @JoinColumn(name = "parent_account_id") on the parentAccount reference did not do anything (I think that Springs injects this automatically so it is already there)

[Mejmo]

I would really like to help you, but I am unable to reproduce. I have the same schema, two entries in linked accounts, one in parent, and I have no loops while querying.

[Lev]

Lombok was indeed the cause of an infinite loop on in-memory model creation and eventually of the StackOverflowError in my case. Nevertheless, I find Lombok's getters and setters generation too useful to give up on it entirely. Hence, I only disabled Lombok generating toString() by adding my own toString() method to a class that just returned super.toString() - and it solved my issue.

[Ena]

You can still use Lombok excluding your lazy fetch fields. @EqualsAndHashCode(exclude={"firstLazyField","secondLazyFiel‌​d"}) and @ToString(exclude={"firstLazyField","secondLazyField"})

[Sida Zhou]

This is also nice: stackoverflow.com/a/47118403/2202107

[Yoeri Van Nieuwerburg]

As @Ena stated, you can indeed use the exclusions. Mind that in lombok you could also use @EqualsAndHashcode.Include on field level. If you do this, DO NOT forget to either remove the class-level @EqualsAndHashcode or tell lombok to only include the explicitly included fields by setting @EqualsAndHashCode(onlyExplicitlyIncluded = true) on class level. P.S.: instead of the exclude list on @ToString, you could also add @ToString.Exclude on a field