无法将 MySql 查询（多对多关系）转换为 HQL

Question

There are 3 entities: 1) Question, 2) Tag and join table between them - Question_Has_Tag

Same objects in java except join table. Instead of it are:

public class Question {
  //
  @ManyToMany(fetch = FetchType.LAZY)
  @JoinTable(name = "question_has_tag",
        joinColumns = @JoinColumn(name = "question_id"),
        inverseJoinColumns = @JoinColumn(name = "tag_id"))
  private List<Tag> tags;

public class Tag {
  //
  @ManyToMany(mappedBy = "tags", fetch = FetchType.LAZY)
  @ContainedIn
  private List<Question> questions;

The query to convert is:

select * from question as q
   join question_has_tag as qht on q.id = qht.question_id
   where qht.question_id in (select question_id from question_has_tag where tag_id = 1);

I'm confusing between the join table and collections. In converting one into another

If u will need more code or information, please let me know

Answer 1

Try this one:

@Entity
public class Question {
    @ManyToMany(mappedBy = "question_has_tag", fetch = FetchType.LAZY)
    private List<Tag> tags;
}

@Entity
public class Tag {
    @ManyToMany(targetEntity = Question.class, fetch = FetchType.LAZY)
    private List<Question> questions;
}

And repository for query results:

@Repository
public interface QuestionRepository extends JpaRepository<Question, Integer> {
  @Query("select q from Question q join Tag t where q.id in (:ids)")
  public List<Question> getQuestionsById(@Param("ids") List<Integer> ids);
}