EJB query language help!!

Question

Hi all, I have been trying to run a ejb query on JBoss 4.0.5, using built in hypersonic db, For some strange reasons am able to fetch all objects from db without any where clause but if am using a where clause with an attribute name from the entitybean am unable to retrieve any results.
I get an org.hibernate.QueryException, could not resolve property : "property name"
My ejb query looks like this...
SELECT template FROM TemplateSelect template WHERE template.template_name='Template_One'
TemplateSelect is my entity bean class and I do have an attribute named template_name in my bean class.
could any one please suggest me what could be wrong and also direct me to a good tutorial on ejb query language as well as I am fairly new to hibernate and ejb3 !
tons of thanks in advance!
pravin

Answer 1

Hi Anuradha ,
I'm afraid the query language does not support retrieving the date portion (i.e. truncating the time) from a date field.
I propose you turn you named into a BETWEEN query taking two parameters one for the beginning of the day and another for the end of the day. Then your named query could look like:
SELECT max(o.req_id) FROM requests o WHERE o.requestdate BETWEEN :start AND :end
The following code creates two calendar instances for the current day, one for 00:00:00 and another for 23:59:59:
Calendar start = Calendar.getInstance();
start.set(Calendar.HOUR_OF_DAY, 0);
start.set(Calendar.MINUTE, 0);
start.set(Calendar.SECOND, 0);
start.set(Calendar.MILLISECOND, 0);
Calendar end = Calendar.getInstance();
end.set(Calendar.HOUR_OF_DAY, 23);
end.set(Calendar.MINUTE, 59);
end.set(Calendar.SECOND, 59);
end.set(Calendar.MILLISECOND, 999);
Here is some sample code that creates a query instance for a named query called findMaxRequestPerDay and passes the Date of the above Calendar instance as actual parameter values. It assumes the named query is called findMaxRequestPerDay and the req_id field is a long:
Query query = em.createNamedQuery("findMaxRequestPerDay");
query.setParameter("start", start.getTime());
query.setParameter("end", end.getTime());
Long max = (Long)query.getSingleResult();
I hope this helps.
Regards Michael