Question

I’m rather new to QueryDSL so this may be an easy one. I have the following structure in my database:

 ______      ___________      _______
| user |    | user2item |    | item  |
|------|    |-----------|    |-------|
| id   |    | user_id   |    | id    |
| name |    | item_id   |    | name  |
 ------      -----------      -------

Now i want to get all users that have at least one item in common with a given user. So i tried:

JPASubQuery subQuery = new JPASubQuery().from(user, item).join(user.items, item).where(user.id.eq(myUserId));
return new JPAQuery(entityManager).from(user).where(user.items.in(subQuery.list(item))).list(user);

But this gives me a problem in the ‘in’ clause because the subquery.list() does not return a List<Item> but a ListSubQuery<Item>. Any help would be really appreciated.

EDIT

Thanks Timo, your suggestion works – but unfortunately if you have more than one subqueries of this kind the resulting statement is much slower than:

User myUser = repository.findOne(myUserId);

return new JPAQuery(entityManager)
           .from(user)
           .join(user.items, item)
           .where(item.in(myUser.getItems()))
           .list(user);

Answer 1

Try this instead

JPASubQuery subQuery = new JPASubQuery()
  .from(user, item).join(user.items, item)
  .where(user.id.eq(myUserId));
return new JPAQuery(entityManager).from(user)
  .where(user.items.any().in(subQuery.list(item))).list(user);