CODEWITHSUNDEEP
javaspringspring-bootjpaspring-data-jpa
dramcio
dramcio

Reputation: 641

Create spring repository without entity

I want to use spring data repository interface to execute native queries - I think this way is the simplest because of low complexity.

But when extending interface ex. CrudRepository<T, ID> I need to write T - my entity, which is not available.

My native queries does not return any concrete entity, so what is the best way to create spring repository without entity?

Upvotes: 57

Views: 66389

Answers (7)

varad thokal
varad thokal

Reputation: 1

If you want to use JPA without implementing your own Entity Manager: Even if your native query does not return a concrete entity, Create a dummy entity. Use that here: CrudRepository<DummyEntity, ID> Then use

@Query("<query here>", nativeQuery=true)
CustomInterfaceType methodName()

in your repository interface.

You also need to create an interface with getter methods for the columns you are selecting in your query. This order should match with what is there in the query.

Upvotes: 0

gagarwa
gagarwa

Reputation: 1492

Currently there is no functionality in JPA to create repositories with only native or JPQL/HQL queries (using @Query notation). To get around this, you can create a dummy object to insert into the extension interface like below:

@Entity
public class RootEntity {
    @Id
    private Integer id;
}

@Repository
public interface MyRepository extends JpaRepository<RootEntity, Integer> {
}

Upvotes: 23

Adam Hughes
Adam Hughes

Reputation: 16309

This works for us. See the entity manager

https://www.baeldung.com/hibernate-entitymanager

@Repository
public class MyRepository {

    @PersistenceContext
    EntityManager entityManager;

    public void doSomeQuery(){
        Query query = entityManager.createNativeQuery("SELECT foo FROM bar");
        query.getResultsList()
        ...
    }

}

Upvotes: 11

Manas
Manas

Reputation: 958

I think that using JdbcTemplate can be considered as an alternative when you do not have a concrete entity class for the resultset of a native query. Querying data using JdbcTemplate requires a POJO class for the resultset and a mapper implementing the RowMapper interface for the POJO class.

Upvotes: 2

Jes&#250;s David L&#243;pez
Jes&#250;s David L&#243;pez

Reputation: 41

If you are using JPA you need Entities. As previous answers you can create NativeQueries or use Criteria API directly from EntityManager.

Some documentation about custom reports and common repo behaviour:

https://docs.spring.io/spring-data/data-commons/docs/1.6.1.RELEASE/reference/html/repositories.html#repositories.custom-behaviour-for-all-repositories

Upvotes: 1

Mehdi Benmesssaoud
Mehdi Benmesssaoud

Reputation: 534

You can just annotate your implementation with @Repository, and get an instance of EntityManager. 

public interface ProductFilterRepository {
    Page<Product> filter(FilterTO filter, Pageable pageable);
}



@Repository
@AllArgsConstructor
public class ProductFilterRepositoryImpl implements ProductFilterRepository {

    private final EntityManager em;

    @Override
    public Page<Product> filter(FilterTO filter, Pageable pageable) {
        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery<Product> cq = cb.createQuery(Product.class);
        Root<Product> root = cq.from(Product.class);
        List<Predicate> predicates = new ArrayList<>();

        if (filter.getPriceMin() != null) {
            predicates.add(cb.ge(root.get("price"), filter.getPriceMin()));
        }
        if (filter.getPriceMax() != null) {
            predicates.add(cb.le(root.get("price"), filter.getPriceMax()));
        }
        if (filter.getBrands() != null && !filter.getBrands().isEmpty()) {
            predicates.add(root.get("brand").in(filter.getBrands()));
        }
        if (filter.getCategories() != null && !filter.getCategories().isEmpty()) {
            predicates.add(root.get("category").in(filter.getCategories()));
        }
        cq.where(predicates.toArray(new Predicate[0]));
        TypedQuery<Product> tq = em.createQuery(cq);
        tq.setMaxResults(pageable.getPageSize());
        tq.setFirstResult(pageable.getPageNumber() * pageable.getPageSize());

        CriteriaQuery<Long> countCq = cb.createQuery(Long.class);
        countCq.select(cb.count(countCq.from(Product.class)));
        countCq.where(predicates.toArray(new Predicate[0]));
        TypedQuery<Long> countTq = em.createQuery(countCq);
        Long count = countTq.getSingleResult();

        return new PageImpl<>(tq.getResultList(), pageable, count);
    }
}

Upvotes: 5

Maciej Kowalski
Maciej Kowalski

Reputation: 26522

CrudRepository or JpaRepository were not designed to work without an <Entity,ID> pair.

You are better off creating a custom repo, inject EntityManager and query from there:

  @Repository
  public class CustomNativeRepositoryImpl implements CustomNativeRepository {

    @Autowired
    private EntityManager entityManager;

    @Override
    public Object runNativeQuery() {
        entityManager.createNativeQuery("myNativeQuery")
         .getSingleResult();
    }
}

Upvotes: 30

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