Criteria Restriction by date field

Question

I have 2 tables, Partner and Visit. A partner can have many visits, also various in same day. I need to create a Criteria restriction to know how many days the Partner has visits since a given date. So, 2 or more visits in same date must be only one.

Can this be done only by Criteria and Restrictions??

I can get all visits from a date with a criteria like:

Criteria criteria = buildCriteria();
criteria.add(Restrictions.eq(DBConstants.VISIT_COL_VISITOR, partnerVisitor));
criteria.add(Restrictions.ge(DBConstants.VISIT_COL_DATE, startDate));

But now, to filter repeated days, I need something like:

criteria.add(Restrictions.unique(DBConstants.VISIT_COL_DATE));

Any idea?

EDIT: @user23123412 @netik

Visit.java

private Integer id;
private Date date;
private Partner visitor;

// getters + setters

Visit table rows related to partner 1:

ID  VISITOR DATE
1   1       10/10/2014 16:20
20  1       10/10/2014 18:00
45  1       12/10/2014 16:20
71  1       12/10/2014 19:40
89  1       16/10/2014 11:20

The answer I need after the query is a Visit count in different days since a given date.

I.E.: If i launch a query with visitor = 1 and startDate = 12/10/2014 the result MUST be 2, cause row id = 45 and id = 71 have different visits in a same day, so it's only ONE day.

Answer 1

You have three options:

1) If you are not pinned to Critera api, I recommend to use HQL instead of Criteria API

Date d =  new SimpleDateFormat("yyyy-MM-dd").parse("2014-10-12");
Query query = session.createQuery("select count(*) from Visit v where trunc(v.date)=:date and v.visitor.id=:visitorId");
query.setParameter("date", d);
query.setParameter("visitorId", 1L);
Long count =  (Long) query.uniqueResult();

2) If you want to use Criteria API, it's possible to apply sqlRestriction. Unfortunately you will lock to specific database. This example works on HSQLDB

Date d =  new SimpleDateFormat("yyyy-MM-dd").parse("2014-10-12");
Long count = (Long) session.createCriteria(Visit.class)
           .setProjection(Projections.rowCount())
           .add(Restrictions.eq("visitor.id", 1L))
           .add(Restrictions.sqlRestriction("trunc(date)=?", d, org.hibernate.type.StandardBasicTypes.DATE))
           .uniqueResult()  ;

3) It's also possible to use pure criteria API, but date restriction must be a little bit hacked (using between restriction)

Date d =  new SimpleDateFormat("yyyy-MM-dd").parse("2014-10-12");
Date maxDate = new Date(d.getTime() + TimeUnit.DAYS.toMillis(1));
Long count = (Long) session.createCriteria(Visit.class)
                .setProjection(Projections.rowCount())
                .add(Restrictions.eq("visitor.id", 1L))
                .add(Restrictions.between("date", d, maxDate))
                .uniqueResult();