Working with Hibernate Queries

Question

I am new to hibernate queries, and trying to get a grasp on how everything works. I am using Hibernate 3 with Netbeans 6.5.

I have a basic project set up and have been playing around with how to do everything. I started with essentially a search query. Where the user can enter values into one or more fields.

The table would be Person with the columns first_name, middle_name, last_name for the sake of the example.

The first way I found was to have a method that took firstName, middleName, and lastName as parameters:

Session session = HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx = session.beginTransaction();
String query = "from Person where (first_name = :firstName or :firstName is null) "+
               "and (middle_name = :middleName or :middleName is null) "
               "and (last_name = :lastname or :lastName is null)";
Query q = session.createQuery(query);
q.setString("firstName", firstName);
q.setString("middleName", middleName);
q.setString("lastName", lastName);
List<Person> results = (List<Person>) q.list();

This did not sit well with me, since it seemed like I should not have to write that much, and well, that I was doing it wrong. So I kept digging and found another way:

Session session = HibernateUtil.getSessionFactory().getCurrentSession();
Transaction tx = session.beginTransaction();
Criteria crit = session.createCriteria(Person.class);
if (firstName != null) {
     crit.add(Expression.eq("firstName", firstName);
}
if (middleName != null) {
     crit.add(Expression.eq("middleName", middleName);
}
if (lastName != null) {
     crit.add(Expression.eq("lastName", lastName);
}
List<Person> results = (List<Person>) crit.list();

So what I am trying to figure out is which way is the preferred way for this type of query? Criteria or Query? Why?

I am guessing that Criteria is the preferred way and you should only use Query when you need to write it by hand for performance type reasons. Am I close?

Answer 1

Criteria is the preferred way. It uses Prepared Statements in the background, so you don't need to worry about SQL injection.

Answer 2

Criteria is the newer way. It was introduced after the hql query layer. Underneath the Criteria api still generates hql. I tend to use the Criteria api because the code looks cleaner and its easier to maintain.

Answer 3

I believe its very common to write queries, specially when you want to make complex inquires, Hibernate has its own query language.

Check Hibernate Query Language HQL

Answer 4

Criteria is the best way to make dynamic queries. No need for null checks on a parameter, just don't add that criteria.