H2 doesn't work properly with @ManyToMany in test profile

[Bruno Oliveira]

Hey Folks! How are you all doing?

I found a problem and a temporary solution in my project. But now, I need to definetly solve the problem. I am noob here. But I intend to contribute a lot in this group.

Let's go to my question: I have a Spring Boot project that contains two classes with a ManyToMany relationship. The entities are Book and Author.

I created three profiles in it: test, dev and prod. All configurations for H2 Database are in the application-test.properties file:

spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.hibernate.ddl-auto=create

And, in the application.properties file, I did this way:

spring.profiles.active=${APP_PROFILE:test}
spring.jpa.open-in-view=false

It worked for several endpoints but when I do GET to retrieve all books by the author's name, I get a 500 status code, and in my IDE (IntelliJ) I have this:

Hibernate:
    select
        distinct book0_.id as id1_1_,
        book0_.book_genre as book_gen2_1_,
        book0_.isbn as isbn3_1_,
        book0_.language as language4_1_,
        book0_.print_length as print_le5_1_,
        book0_.publication_year as publicat6_1_,
        book0_.publisher as publishe7_1_,
        book0_.synopsis as synopsis8_1_,
        book0_.title as title9_1_,
        book0_.url_cover as url_cov10_1_
    from
        tb_book book0_
    inner join
        tb_book_author authors1_
            on book0_.id=authors1_.book_id
    inner join
        tb_author author2_
            on authors1_.author_id=author2_.id
    where
        author2_.name like ? limit ?
2021-07-02 17:54:07.806  WARN 16158 --- [nio-8080-exec-6] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: Could not write JSON: failed to lazily initialize a collection of role: com.bruno.project.entities.Book.authors, could not initialize proxy - no Session; nested exception is com.fasterxml.jackson.databind.JsonMappingException: failed to lazily initialize a collection of role: com.bruno.project.entities.Book.authors, could not initialize proxy - no Session (through reference chain: org.springframework.data.domain.PageImpl["content"]->java.util.Collections$UnmodifiableRandomAccessList[0]->com.bruno.project.entities.Book["authors"])]

The temporary solution I found was changing the content of the application.properties file, this way:

spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=
spring.datasource.driver-class-name=org.h2.Driver

spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.hibernate.ddl-auto=create

That way, all endpoints run perfectly. But I will deploy my code into Heroku platform and it would be very good if I could user different profiles.

Have you ever experienced this situation? May you help me?

Thanks in advance!

Bruno