Spring Data JPA, Hibernate, @ManyToOne(fetch=FetchType.LAZY) and org.hibernate.LazyInitializationException: could not initialize proxy - no Session

Question

How to make Hibernate Lazy initialization to work (within Spring Boot)?

org.hibernate.LazyInitializationException: could not initialize proxy - no Session
    at org.hibernate.proxy.AbstractLazyInitializer.initialize(AbstractLazyInitializer.java:165) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at org.hibernate.proxy.AbstractLazyInitializer.getImplementation(AbstractLazyInitializer.java:286) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer.invoke(JavassistLazyInitializer.java:185) ~[hibernate-core-4.3.11.Final.jar:4.3.11.Final]
    at com.example.domain.Employee_$$_jvstb7e_2.toString(Employee_$$_jvstb7e_2.java) ~[bin/:na]
    at java.lang.String.valueOf(String.java:2994) ~[na:1.8.0_74]
    at java.lang.StringBuilder.append(StringBuilder.java:131) ~[na:1.8.0_74]
    at com.example.domain.Phone.toString(Phone.java:13) ~[bin/:na]
    at com.example.SpringBootQuerydslTestBean$1.run(SpringBootQuerydslTestBean.java:49) ~[bin/:na]
    at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:806) [spring-boot-1.3.5.RELEASE.jar:1.3.5.RELEASE]
    ... 6 common frames omitted

Java code

public class Phone {
    ...
    @ManyToOne(fetch=FetchType.LAZY)
    private Employee owner;

P.S. Some advises to use FetchType.EAGER like in org.hibernate.LazyInitializationException: could not initialize proxy - no Session, but making Lazy loading work (within Spring Boot, Spring Data JPA) is exactly my goal.

Do you have repository.impl classes?? You can fetch data from JPA query. — Manu AG
– Manu AG, Commented Jun 23, 2016 at 7:21
Create a proper toString that doesn't include the back reference. The issue is you are logging something (I guess)... Again potentially dangerous as when it would work you probably would run into a stack overflow exception due to Pone referencing Employee which has a toString probably referencing Phone again and gain and again. — M. Deinum
– M. Deinum, Commented Jun 23, 2016 at 7:24

Paul Verest · Accepted Answer · 2016-06-23 07:39:27Z

3

Thanks to M. Deinum for hint.

This particular case was solved by adding toString() in Employee to re-define over Lombok toString()

@Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";
    }

also specifying exactly Fetch type

code at https://github.com/paulvi/spring-boot-querydsl

answered Jun 23, 2016 at 7:39

Paul Verest

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M. Deinum Over a year ago

You could also use Lombok and just explicitly exclude the employee field from Phone which should do the trick.

Marcell Rico · Accepted Answer · 2018-04-02 17:21:07Z

1

This is happening because of the Lombok instruction @Data, instead of it, use @Getter and @Setter, Follow javadocs from @Data:

Equivalent to @Getter @Setter @RequiredArgsConstructor @ToString @EqualsAndHashCode.

The instruction @ToString generate a implementation of toString method for entire class, so in your JPA return needs to have data for all the object.

answered Apr 2, 2018 at 17:21

Marcell Rico

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Comments

sriam980980 · Accepted Answer · 2016-06-23 07:19:38Z

0

I think you are trying to get the childs from the proxy when the current session is detached , you can get the lazy childs in the same session .

answered Jun 23, 2016 at 7:19

sriam980980

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1 Comment

Paul Verest Over a year ago

How to control sessions(that are Hibernate things) from Spring Boot that uses Spring Data repositories over JPA?

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