Java Hibernate Criteria returning only one entity fields

Question

i have a simple Criteria which is used by get the school of a student which i have the ID i need only the school not the student i have a simple coding like

public School loadSchool(Integer studentID) 
{        
    final Session session = getHibernateTemplate().getSessionFactory().openSession();
    final Criteria like = session.createCriteria(Student.class)
    .add(idEq(studentID))
    .setFetchMode("School",FetchMode.JOIN); 
    final School retValue = ((Student)like.uniqueResult()).getSchool();
    session.close();
    return retValue;
}

as you can see i retrieve the Student and the School as well i need only the School my question are

1). there is a way other than setProjections() that i could extract[retrieve from the DB] only the School fields not the Student fields because are to many fields and is a kind annoying listing all the fields in setProjection and affects performance something like

setProjectionOnlyPropertiesForClass(School.class).

2). there is any workaround.

thanks a lot.

isnot2bad · Accepted Answer · 2013-09-24 13:42:51Z

1

The problem is that you're querying Student objects instead of School objects! The corresponding HQL query is:

select student
from Student student join student.school
where student.id=:studentId

Instead, you should query for School objects:

select school
from School school, Student student
where student.school = school and student.id=:studentId

(Maybe you should use HQL instead of criteria queries for that - they are simpler to write and understand).

answered Sep 24, 2013 at 13:42

isnot2bad

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