ass1-jpa/src/main/java/dst/ass1/jpa/dao/impl/CourseDAO.java

   1 package dst.ass1.jpa.dao.impl;
   2
   3 import dst.ass1.jpa.dao.ICourseDAO;
   4 import dst.ass1.jpa.model.CourseStatus;
   5 import dst.ass1.jpa.model.ICourse;
   6 import dst.ass1.jpa.model.impl.Course;
   7 import dst.ass1.jpa.util.Constants;
   8
   9 import javax.persistence.EntityManager;
  10 import javax.persistence.NoResultException;
  11 import javax.persistence.criteria.CriteriaBuilder;
  12 import javax.persistence.criteria.CriteriaQuery;
  13 import javax.persistence.criteria.Predicate;
  14 import javax.persistence.criteria.Root;
  15 import java.util.ArrayList;
  16 import java.util.Collection;
  17 import java.util.Date;
  18 import java.util.List;
  19
  20 public class CourseDAO extends GenericDAO<Course, ICourse> implements ICourseDAO {
  21     public CourseDAO(EntityManager em) {
  22         super(em, Course.class);
  23     }
  24
  25     @Override
  26     public Collection<ICourse> findOngoingAndFreeCoursesForPlatform(String platformName) {
  27         try {
  28             return em.createNamedQuery(Constants.Q_ONGOING_AND_FREE_PLATFORM_COURSES, ICourse.class)
  29                     .setParameter("platformName", platformName).getResultList();
  30         } catch (NoResultException e) {
  31             return null;
  32         }
  33     }
  34
  35     @Override
  36     public Collection<ICourse> findNonCancelledCoursesBetweenStartAndEnd(Date start, Date end) {
  37         CriteriaBuilder b = em.getCriteriaBuilder();
  38         CriteriaQuery<ICourse> q = b.createQuery(ICourse.class);
  39         Root<Course> root = q.from(Course.class);
  40         final List<Predicate> andPredicates = new ArrayList<Predicate>();
  41
  42         andPredicates.add(b.notEqual(root.get("status"), CourseStatus.CANCELLED));
  43         if (start != null) andPredicates.add(b.greaterThan(root.get("start"), start));
  44         if (end != null) andPredicates.add(b.lessThan(root.get("end"), end));
  45
  46         q.select(root).where(b.and(andPredicates.toArray(new Predicate[andPredicates.size()])));
  47
  48         List<ICourse> a = em.createQuery(q).getResultList();
  49         return a;
  50     }
  51 }