How can the proper Solution (answered Jun 27, 2018 at 6:01 from user Vlad Mihalcea) https://stackoverflow.com/a/51055523/19408825 be transfered in Hibernate commands instead of query Strings? The proper sample solution:
List<Post> posts = entityManager
.createQuery(
"select distinct p " +
"from Post p " +
"left join fetch p.comments " +
"where p.id between :minId and :maxId ", Post.class)
.setParameter("minId", 1L)
.setParameter("maxId", 50L)
.setHint(QueryHints.PASS_DISTINCT_THROUGH, false)
.getResultList();
posts = entityManager
.createQuery(
"select distinct p " +
"from Post p " +
"left join fetch p.tags t " +
"where p in :posts ", Post.class)
.setParameter("posts", posts)
.setHint(QueryHints.PASS_DISTINCT_THROUGH, false)
.getResultList();
According to coding guidlines we must use Hibernate commands instead of the Strings. I already put weeks of work into it and one of my 50 different trials (which are not working) look something like the following.
Class Post:
// Post Class with two lists that are needed in the same time
public class Post {
...
@OneToMany(mappedBy = "post", fetch = FetchType.LAZY)
private List<Comment> comments;
@OneToMany(mappedBy = "post", fetch = FetchType.LAZY)
private List<Tag> tags;
...
}
Class PostService:
public class PostService {
...
public List<Post> findingAllPosts() {
CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Post> criteria = builder.createQuery(Post.class);
Root<Post> root = criteria.from(Post.class);
root.fetch(Post_.comments, JoinType.LEFT);
criteria.select(root);
criteria.distinct(true);
List<Post> posts = entityManager
.createQuery(criteria)
.setHint(QueryHints.HINT_PASS_DISTINCT_THROUGH, false)
.getResultList();
root.fetch(Post_.tags, JoinType.LEFT);
// different approaches ... one is:
criteria.select(root)
.where(root
.in(":posts")
);
posts = entityManager
.createQuery(criteria)
.setParameter("posts", posts)
.setHint(QueryHints.HINT_PASS_DISTINCT_THROUGH, false)
.getResultList();
return posts;
}
}
This and similar other Trials throw the Exception:
org.hibernate.QueryException:
query specified join fetching, but the owner of the
fetched association was not present in the select list
[FromElement{explicit,not a collection join,fetch join,
fetch non-lazy properties,
classAlias=generatedAlias1,
role=at.test.Post.comments,
tableName=TEST.COMMENT,
tableAlias=comment1_,
origin=TEST.POST post0_,columns={post0_.ID ,className=at.test.Comment}}]
[
select distinct generatedAlias0
from at.test.Post as generatedAlias0
left join fetch generatedAlias0.comments as generatedAlias1
left join fetch generatedAlias0.tags as generatedAlias0
where generatedAlias0 in (:param0)
]:
javax.ejb.EJBTransactionRolledbackException:
org.hibernate.QueryException:
query specified join fetching, but the owner of the
fetched association was not present in the select list
[FromElement{explicit,not a collection join,fetch join,
fetch non-lazy properties,
classAlias=generatedAlias1,
role=at.test.Post.comments,
tableName=TEST.COMMENT,
tableAlias=comment1_,
origin=TEST.POST post0_,
columns={post0_.ID ,className=at.test.Comment}}]
[
select distinct generatedAlias0
from at.test.Post as generatedAlias0
left join fetch generatedAlias0.comments as generatedAlias1
left join fetch generatedAlias0.tags as generatedAlias0
where generatedAlias0 in (:param0)]
Where I am unsure is, how I use the "in" clause in Hibernate. Maybe there is an Problem in the line
... "where p in :posts ", Post.class)
which I translated to
... .where(root.in(":posts"));
Does anybody know how to use the "in"-Clause in the right way? Or how can this Query Strings can be translated to Hibernate commands like I tried?
Thanks a lot in advance! Would be very important.
