How do I implement a Criteria API method along with JpaRepository interface? (Spring Boot)

Question

I need to implement one more method to my JpaRepository, but this one has many criterias and I would like to use Criteria API. But I can`t browse, how to do it in elegant way. So my question is in other words: Could I add a method to my JpaRepository interface and implement it somehow, to use it like generated methods?

I tried to implement this repo interface, but compiler makes me implement all methods.

Answer 1

If you want to use criteria in JPA you can go with JPA Specification/Predicates.

As you can add multiple conditions to it in your repository and return the expected results.

for example - under your service layer call a JPA method naming anything you want and pass the argument to it if you want to.

like :-

(result is in list case) - Service layer

List<your Generic> list = yourRepository.yourMethodName(your Argument);

Repository layer

default List<your Generic> yourMethodName(your Argument session) {
        return findAll(new Specification<your Generic>() {
            private static final long serialVersionUID = 1L;

            @Override
            public Predicate toPredicate(Root<your Generic> root, CriteriaQuery<?> query, CriteriaBuilder criteriaBuilder) {
                List<Predicate> predicates = new ArrayList<>();

                //your condition will be here-------
                //for example --
                if (session.getUserType().equalsIgnoreCase("ADMIN")) {
                    predicates.add(
                            criteriaBuilder.and(criteriaBuilder.equal(root.get("userLevel"), 3)));

                    predicates.add(criteriaBuilder
                        .and(criteriaBuilder.equal(root.get("isActive"), "Yes")));
                }
                
                //and many more conditions you can use here to get the expected data... like and, or, like, ge, equal, etc...
                return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
            }
        });
    }

for different criteria queries you can refer - https://www.baeldung.com/spring-data-criteria-queries

https://www.baeldung.com/jpa-and-or-criteria-predicates

if still any issue please let me know down in the comment