I have three entities with relations.

public class Site {
    @OneToMany
    private List<Page> pages;
}

public class Page {
    @OneToMany
    private List<Article> articles;

    @OneToMany
    private List<TopArticle> topArticles;
}

public class Article {
    @ManyToOne
    private Page page;
}

public class TopArticle {
    @ManyToOne
    @JoinColumn(name = "PageId")
    private Page page;
    
    @OneToOne
    @JoinColumn(name = "ArticleId")
    private Article article;
}

Fields page and arctile in TopArticle have database restrictions - NOT NULL. (Resctrictions are required)

I have to save Site with all associations.

    Article article = new Article();
    TopArticle topArticle = new TopArticle();

    Page page = new Page();
    page.getArticles().add(article);
    page.getTopArticles().add(topArticle);

    Site site = new Site();
    site.getPages().add(page);

    siteDAO.save(site);

Sometimes it saves site.
But sometimes it throws an error.

com.microsoft.sqlserver.jdbc.SQLServerException: Cannot insert the value NULL into column 'ArticleId', table '...TopArticle'; column does not allow nulls. INSERT fails

It seems that after Page is saved, it tries to save associations List<Article> articles and List<TopArticle> topArticles.
Perhaps, when List<Article> articles are saved before List<TopArticle> topArticles it works.
In another way it fails.

Questions:

Is an issue in saving properties order in JPA?

How can I enforce Hibernate to save articles before topArticles?

Is there any other solutions?

Thanks

With a bi-directional relationship it is your responsibility to ensure both sides are set correctly on the in-memory model otherwise you will get the error you are seeing.

So you need to call:

article.setPage(page);

And ideally you should encapsulate the operation so the in-memory model is always consistent:

public class Page{

    public List<Article> getArticles(){
      return Collections.unmodifiableList(articles); //force through add method
    }

    public void addArticle(Article article){
        articles.add(article);
        article.setPage(this);
    }
}