QueryDSL, specify projection for join-CodePudding

I'm trying to use QueryDSL to fetch a collection of entities (table Category) where each entity has a @OneToMany association with an other type of entity (table User), and a join is used to get it all in one go.

Problem is that the second entity (the users) contains CLOB fields which should not be included. I don't want to include them in my query. Given the following QueryDSL query :

JPAQuery<CategoryEntity> baseQuery = new JPAQuery<>(entityManager)
                .select(QCategoryEntity.categoryEntity)
                .from(QCategoryEntity.categoryEntity)
                .leftJoin(QCategoryEntity.categoryEntity.users, QUserEntity.userEntity)
                .where(somePredicate);

QueryDSL will generate something like

SELECT categoryen0_.id, (...), useren0_.id, (...) 
FROM category categoryen0 
LEFT OUTER JOIN user useren0 ON ...
WHERE ...

How can a specific projection be applied to this query such that the CLOB data is excluded?

Notes :

I'm trying to avoid native queries and changing the domain model.
I have not found a way to use Projections on the join itself.
Using subqueries inside joins is not supported by JPQL hence it's not supported by QueryDSL either.

CodePudding user response：

Turns out this was not working well due to my use of fetch joins, which prevented me from using projections. Solving it was a matter of using a basic join instead and manually reconstructing the relationship.

Collection<Tuple> tuples = new JPAQuery<>(entityManager)
                .select(QCategoryEntity.categoryEntity, Projections.constructor(UserEntity.class, <constructor arguments>)
                .from(QCategoryEntity.categoryEntity)
                .join(QCategoryEntity.categoryEntity.users, QUserEntity.userEntity)
                .where(somePredicate);