TubeRepositoryImpl

package metubeV2.repository;

import metubeV2.domain.entities.Tube;
import metubeV2.repository.interfaces.TubeRepository;

import javax.inject.Inject;
import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Root;
import java.util.List;
import java.util.Optional;

import static metubeV2.constants.Constants.PARAMETER_ID;

public class TubeRepositoryImpl implements TubeRepository {

    private final EntityManager entityManager;

    @Inject
    public TubeRepositoryImpl(EntityManager entityManager) {
        this.entityManager = entityManager;
    }

    @Override
    public Tube save(Tube entity) {
        this.entityManager.getTransaction().begin();
        this.entityManager.persist(entity);
        this.entityManager.getTransaction().commit();

        return entity;
    }

    @Override
    public List<Tube> findAll() {
        CriteriaBuilder criteriaBuilder = this.entityManager
                .getCriteriaBuilder();
        CriteriaQuery<Tube> criteriaQuery = criteriaBuilder
                .createQuery(Tube.class);
        Root<Tube> root = criteriaQuery.from(Tube.class);

        criteriaQuery.select(root);

        return this.entityManager
                .createQuery(criteriaQuery)
                .getResultList();
    }

    @Override
    public Optional<Tube> findById(String id) {
        return getEntityByParameter(id, PARAMETER_ID);
    }

    @Override
    public Tube update(Tube tube) {
        this.entityManager.getTransaction().begin();
        this.entityManager.merge(tube);
        this.entityManager.getTransaction().commit();

        return tube;
    }

    private Optional<Tube> getEntityByParameter(String name,
                                                String parameterName) {
        CriteriaBuilder criteriaBuilder = this.entityManager
                .getCriteriaBuilder();
        CriteriaQuery<Tube> criteriaQuery = criteriaBuilder
                .createQuery(Tube.class);
        Root<Tube> root = criteriaQuery.from(Tube.class);

        criteriaQuery.select(root)
                .where(criteriaBuilder
                        .equal(root.get(parameterName), name));

        try {
            return Optional.ofNullable(this.entityManager
                    .createQuery(criteriaQuery)
                    .getSingleResult());

        } catch (NoResultException ignored) {
            return Optional.empty();
        }
    }
}