JPA criteria query in a many-to-many relationship

Question

I\'m using JPA 2.0 in EclipseLink 2.3.2 in which I have a many-to-many relationship between products and their colours. A product can have many colours and a colour can be a

Answer 1

The following is the criteria query regarding NOT IN() (I however, prefer NOT EXISTS() over NOT IN()).

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Colour>criteriaQuery=criteriaBuilder.createQuery(Colour.class);
Metamodel metamodel = entityManager.getMetamodel();
EntityType<Colour> entityType = metamodel.entity(Colour.class);
Root<Colour> root = criteriaQuery.from(entityType);
criteriaQuery.select(root);

Subquery<Long>subquery=criteriaQuery.subquery(Long.class);
Root<Product> subRoot = subquery.from(Product.class);
subquery.select(root.get(Colour_.colourId));

Predicate paramPredicate = criteriaBuilder.equal(subRoot.get(Product_.prodId), prodId);
Predicate correlatePredicate = criteriaBuilder.equal(root.get(Colour_.productSet), subRoot);

subquery.where(criteriaBuilder.and(paramPredicate, correlatePredicate));
criteriaQuery.where(criteriaBuilder.in(root.get(Colour_.colourId)).value(subquery).not());
criteriaQuery.orderBy(criteriaBuilder.desc(root.get(Colour_.colourId)));

TypedQuery<Colour> typedQuery = entityManager.createQuery(criteriaQuery);
List<Colour> list=typedQuery.getResultList();

This produces the following SQL query.

SELECT t0.colour_id, t0.colour_hex, t0.colour_name 
FROM projectdb.colour t0 
WHERE NOT 
(t0.colour_id IN (
                 SELECT t0.colour_id 
                 FROM prod_colour t3, projectdb.product t2, projectdb.product t1 
                 WHERE (((t1.prod_id = ?) 
                 AND (t1.prod_id = t2.prod_id)) 
                 AND ((t3.colour_id = t0.colour_id) 
                 AND (t2.prod_id = t3.prod_id))))) 
ORDER BY t0.colour_id DESC

This query returns the desired result set. It however, produces a redundant join as can be seen but this seems to be a bug.

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Edit:

Trying the same query on Hibernate, the way of writing this criteria query looks incorrect. A combination of join and subquery result in producing the correct SQL query.

CriteriaBuilder criteriaBuilder=entityManager.getCriteriaBuilder();
CriteriaQuery<Colour>criteriaQuery=criteriaBuilder.createQuery(Colour.class);
Metamodel metamodel = entityManager.getMetamodel();
EntityType<Colour> entityType = metamodel.entity(Colour.class);
Root<Colour> root = criteriaQuery.from(entityType);
criteriaQuery.select(root);

Subquery<Long>subquery=criteriaQuery.subquery(Long.class);
Root<Colour> subRoot = subquery.from(Colour.class);
subquery.select(subRoot.get(Colour_.colourId));
SetJoin<Colour, Product> join = subRoot.join(Colour_.productSet, JoinType.INNER);

ParameterExpression<Long> parameterExpression=criteriaBuilder.parameter(Long.class);
criteriaQuery.where(criteriaBuilder.in(root.get(Colour_.colourId)).value(subquery).not());
subquery.where(criteriaBuilder.equal(join.get(Product_.prodId), parameterExpression));
criteriaQuery.orderBy(criteriaBuilder.desc(root.get(Colour_.colourId)));

TypedQuery<Colour> typedQuery = entityManager.createQuery(criteriaQuery);
List<Colour> list = typedQuery.setParameter(parameterExpression, 1L).getResultList();

This produces the following SQL query which would in turn be delegated to MySQL.

SELECT t0.colour_id, t0.colour_name, t0.colour_hex
FROM projectdb.colour t0
WHERE NOT (t0.colour_id IN 
          (SELECT t1.colour_id
           FROM prod_colour t3, projectdb.product t2, projectdb.colour t1
           WHERE ((t2.prod_id = ?)
           AND ((t3.colour_id = t1.colour_id)
           AND (t2.prod_id = t3.prod_id)))))
ORDER BY t0.colour_id DESC