从带有参数的JPQL查询中选择全部

Question

I have selection parameters on flat data, only don't know how to either omit a parameter entirely, or make it a complete wildcard. The search might use one or all parameters. How is this done? With ANY or ALL ? Or, is there another way?

I would like to use one general query with all the paremeters, and pass in "all" or "any", something along those lines, for some of those parameters.

existing code:

package legacy.database;

import java.sql.Timestamp;
import java.util.List;
import java.util.logging.Logger;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

public class MyQueries {

    private static final Logger log = Logger.getLogger(MyQueries.class.getName());
    private final EntityManagerFactory emf = Persistence.createEntityManagerFactory("LegacyDatabasePU");
    private final EntityManager em = emf.createEntityManager();

    public MyQueries() {
    }

    public List<Clients> findAll() {
        Query q = em.createQuery("select c from Clients c");
       List<Clients> clients = q.getResultList();
        return clients;
    }

    public List<Clients> selectWithParameters(Criteria c) {
        log.info(c.toString());
        String opener = c.getOpener();
        String closer1 = c.getCloser1();
        String status = c.getStatus();
        Query q = em.createQuery(
                "SELECT c FROM Clients c "
                + "WHERE c.status like :status "
                + "and c.closer1 like :closer1 "
                + "and c.opener like :opener");
        q.setParameter("opener", opener);
        q.setParameter("closer1", closer1);
        q.setParameter("status", status);
        log.info(q.toString());
        List<Clients> clients = q.getResultList();
        log.fine(clients.toString());
        return clients;
    }

    public Clients findById(int id) {
        Clients client = em.find(Clients.class, id);
        return client;
    }

    public void send(int id) {
        Clients c = em.find(Clients.class, id);
        java.util.Date date = new java.util.Date();
        Timestamp t = new Timestamp(date.getTime());
        em.getTransaction().begin();
        c.setDateUpdated(t.toString());
        em.getTransaction().commit();
    }
}

Answer 1

In case the parameters are optional, the criteria API provides some more flexibility. If the selectWithParameters is called often, consider using parameters, since the DB can cache the parametrized query then.

selectWithParameters with optional parameters reads like this:

public List<Clients> selectWithParameters(Criteria criteria) {
    log.info(criteria.toString());
    String opener = criteria.getOpener();
    String closer1 = criteria.getCloser1();
    String status = criteria.getStatus();

    CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
    CriteriaQuery<Clients> query = criteriaBuilder.createQuery(Clients.class);
    Root<Clients> c = query.from(Clients.class);
    List<Predicate> wherePredicates = new LinkedList<Predicate>();
    if (null != status) {
        wherePredicates.add(criteriaBuilder.like(c.get("status"), status));
    }
    if (null != closer1) {
        wherePredicates.add(criteriaBuilder.like(c.get("closer1"), closer1));
    }
    if (null != opener) {
        wherePredicates.add(criteriaBuilder.like(c.get("opener"), opener));
    }
    query.where(wherePredicates.toArray(new Predicate[0]));

    List<Clients> clients = em.createQuery(query).getResultList();
    log.fine(clients.toString());
    return clients;
}

Answer 2

Thank you, Heiner. This worked, not sure why I had trouble with Heiner's code, but his sample put me in the right direction:

public List<Clients> selectByCriteria(Criteria criteria) {
    CriteriaBuilder criteriaBuilder = em.getCriteriaBuilder();
    CriteriaQuery<Clients> clientCriteriaQuery = criteriaBuilder.createQuery(Clients.class);
    Root<Clients> clientRoot = clientCriteriaQuery.from(Clients.class);
    clientCriteriaQuery.select(clientRoot);
    List<Predicate> predicates = new ArrayList<>();
    predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.phone1), "%" + criteria.getPhone1() + "%"));
    if (!criteria.getOpener().equalsIgnoreCase("all")) {
        predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.opener), "%" + criteria.getOpener() + "%"));
    }
    if (!criteria.getCloser1().equalsIgnoreCase("all")) {
        predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.closer1), "%" + criteria.getCloser1() + "%"));
    }
    if (!criteria.getStatus().equalsIgnoreCase("all")) {
        predicates.add(criteriaBuilder.like(clientRoot.get(Clients_.status), "%" + criteria.getStatus() + "%"));
    }
    clientCriteriaQuery.where(predicates.toArray(new Predicate[0]));
    List<Clients> clients = em.createQuery(clientCriteriaQuery).getResultList();
    return clients;
}

There's probably no substantive difference (?) from what Heiner answered. JPA and JPQL are a bit murky. I can't believe it, but I almost prefer SQL! I'll have to adjust.