How can i get entity object with contion JPA - jpa

Question

I have 2 Objects Site and Page.
A Site have many Pages.
I get pages with fetch Lazy type.
With a particular reason i want to get pages of a site where the date of pages > val.
#Entity
#Table(name = "site")
Public class Site {
String site_id;
Set<Page> pages;
#OneToMany(mappedBy = "site", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
public Set<Page> getPages() {
return pages;
}
}
#Entity
#Table(name = "page")
Public class Page{
String page_id;
Site site;
#ManyToOne(fetch=FetchType.LAZY, cascade = CascadeType.MERGE)
#JoinColumn(name = "site_id")
public Site getSite() {
return site;
}
}
Now in SiteDao i have the mothode to call a site and its pages
#Stateless
public class SiteDao {
#PersistenceContext(unitName = "name")
private EntityManager em;
public Site getSiteAndPages(String site_id) {
Query q = em.createQuery("select s From Site s where s.site_id = :site_id");
q.setParameter("site_id", site_id);
Site s = (Site) q.getSingleResult();
s.getPages();
return s;
}
}
This turns well, but s.getPages() return all the pages and i want to get only some pages using where conditions.
I tried many options like:
Query q = em.createQuery(
"select s, p From Site s"
+ " join s.pages p "
+ " where s.site_id = :site_id "
+ " and p.site = s"
+ " and p.lastupdate > :val"
);
q.setParameter("site_id", site_id);
q.setParameter("val", lastUpdate);
Im bloked after many searches, does any person have an idea about how can i fix this ?
B.R

Answer 1

You need some business methods, you can keep inside Site Class
There are two options
1. Add filter
getLatestPages(Date lastupdate)
{
List pages_= s.getPages();
List latestPages=new ArrayList();
for(Page p: pages_)
{
if(p.getLastUpdatedate().after(lastupdate)) {
latestPages.add(p);
}
}
reutrn latestPages;
}
2.Use query
getLatestPages(EntityManager em, Date lastupdate)
{
Query q = em.createQuery(
"select p From Site s"
+ " join s.pages p "
+ " where s.site_id = :site_id "
+ " and p.site = s"
+ " and p.lastupdate > :val"
);
q.setParameter("site_id", this.site_id);
q.setParameter("val", lastUpdate);
return q.getResultList();
}
Hope this work.