JPA Criteria api query fails while JPQL goes through - jpa

Question

I'm using JPA to manage my persistency layer.
One of my my Criteria API throws an exception. I re-wrote it in JPQL and it works just fine so I guess I missed something in my criteria api version.
Here it is, my criteria api query:
public FoodItemTagsOverrideRule findByFoodItemIdAndType(long foodItemId, RuleTypes ruleType) {
CriteriaQuery<Rule> c = getCriteriaQuery();
Root<Rule> rule =
c.from(Rule.class);
Predicate foodItemIdCondition =
cb.equal(rule.get(Rule_.foodItemId), foodItemId);
Predicate typeCondition =
cb.equal(rule.get(Rule_.ruleType),
ruleType.toString());
c.where(foodItemIdCondition, typeCondition);
TypedQuery<Rule> q =
entityManager.createQuery(c);
List<Rule> result = q.getResultList();
if (result.isEmpty()) {
return null;
}
return result.get(0);
}
The JPQL version that works just fine:
public Rule findByFoodItemIdAndType(long foodItemId, RuleTypes ruleType) {
TypedQuery<Rule> query = getEntityManager().createQuery(
"SELECT rule " + "FROM " + Rule.class.getSimpleName() + " rule " + "WHERE rule.foodItemId = :foodItemId "
+ "AND rule.ruleType = :ruleType", Rule.class);
query.setParameter("foodItemId", foodItemId);
query.setParameter("ruleType", ruleType.toString());
List<Rule> result = query.getResultList();
if (result.isEmpty()) {
return null;
}
return result.get(0);
}
Can you see a difference there? Did I put something wrong in the criteria api query?
Thakns!

Answer 1

You can try the below code. I tried to fit to your code, you can alter accordingly.
CriteriaBuilder qb = em.getCriteriaBuilder();
CriteriaQuery cq = qb.createQuery();
Root<Rule> rule = cq.from(Rule.class);
List<Predicate> predicates = new ArrayList<Predicate>();
predicates.add(qb.equal(rule.get("foodItemId"), foodItemId));
predicates.add(qb.equal(rule.get("ruleType"), ruleType));
cq.select(rule).where(predicates.toArray(new Predicate[]{}));
em.createQuery(cq).getResultList();
Edit : For type-safe predicate definition
predicates.add(qb.equal(rule.get(Rule_.foodItemId), foodItemId));
predicates.add(qb.equal(rule.get(Rule_.ruleType), ruleType));