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

   1 package dst.ass1.jpa.dao.impl;
   2
   3 import dst.ass1.jpa.dao.IMaterialServerDAO;
   4 import dst.ass1.jpa.model.ICourse;
   5 import dst.ass1.jpa.model.IMaterialServer;
   6 import dst.ass1.jpa.model.impl.Lesson;
   7 import dst.ass1.jpa.model.impl.Material;
   8 import dst.ass1.jpa.model.impl.MaterialServer;
   9 import dst.ass1.jpa.util.Constants;
  10
  11 import javax.persistence.EntityManager;
  12 import javax.persistence.criteria.CriteriaBuilder;
  13 import javax.persistence.criteria.CriteriaQuery;
  14 import javax.persistence.criteria.Join;
  15 import javax.persistence.criteria.Root;
  16 import java.util.Collection;
  17 import java.util.List;
  18
  19 public class MaterialServerDAO extends GenericDAO<MaterialServer, IMaterialServer> implements IMaterialServerDAO {
  20     public MaterialServerDAO(EntityManager em) {
  21         super(em, MaterialServer.class);
  22     }
  23
  24     @Override
  25     public Collection<IMaterialServer> findMaterialServersForCourse(ICourse course) {
  26         CriteriaBuilder b = em.getCriteriaBuilder();
  27         CriteriaQuery<IMaterialServer> q = b.createQuery(IMaterialServer.class);
  28
  29         Root<MaterialServer> root = q.from(MaterialServer.class);
  30         Join<MaterialServer, Material> materials = root.join(Constants.A_MATERIALS);
  31         Join<Material, Lesson> lessons = materials.join(Constants.M_MATERIAL_LESSON);
  32
  33         q.select(root).distinct(true);
  34         if (course != null) q.where(lessons.in(course.getLessons()));
  35
  36         List<IMaterialServer> a = em.createQuery(q).getResultList();
  37         return a;
  38     }
  39 }