OrderByUtil.java

package jpasearch.repository.util;

import java.util.ArrayList;
import java.util.List;

import javax.inject.Inject;
import javax.inject.Named;
import javax.inject.Singleton;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.Order;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Root;

import jpasearch.repository.query.OrderBy;
import jpasearch.repository.query.OrderByDirection;

/**
 * Helper to create list of {@link Order} out of {@link OrderBy}s.
 */
@Named
@Singleton
public class OrderByUtil {

    private JpaUtil jpaUtil;

    public <E> List<Order> buildJpaOrders(Iterable<OrderBy<E, ?>> orders, Root<E> root, CriteriaBuilder builder) {
        List<Order> jpaOrders = new ArrayList<>();
        for (OrderBy<E, ?> ob : orders) {
            Path<?> path = jpaUtil.getPath(root, ob.getPath());
            jpaOrders.add(ob.getDirection() == OrderByDirection.DESC ? builder.desc(path) : builder.asc(path));
        }
        return jpaOrders;
    }

    @Inject
    public void setJpaUtil(JpaUtil jpaUtil) {
        this.jpaUtil = jpaUtil;
    }

}