Hibernate: How to set NULL query-parameter value with HQL?

Question

How can I set a Hibernate Parameter to \"null\"? Example:

Query query = getSession().createQuery(\"from CountryDTO c where c.status = :status  and c.type =:t         


        

Answer 1

You can use

Restrictions.eqOrIsNull("status", status)

insted of

status == null ? Restrictions.isNull("status") : Restrictions.eq("status", status)

Answer 2

For an actual HQL query:

FROM Users WHERE Name IS NULL

Answer 3

This is not a Hibernate specific issue (it's just SQL nature), and YES, there IS a solution for both SQL and HQL:

@Peter Lang had the right idea, and you had the correct HQL query. I guess you just needed a new clean run to pick up the query changes ;-)

The below code absolutely works and it is great if you keep all your queries in orm.xml

from CountryDTO c where ((:status is null and c.status is null) or c.status = :status) and c.type =:type

If your parameter String is null then the query will check if the row's status is null as well. Otherwise it will resort to compare with the equals sign.

Notes:

The issue may be a specific MySql quirk. I only tested with Oracle.

The above query assumes that there are table rows where c.status is null

The where clause is prioritized so that the parameter is checked first.

The parameter name 'type' may be a reserved word in SQL but it shouldn't matter since it is replaced before the query runs.

If you needed to skip the :status where_clause altogether; you can code like so:

from CountryDTO c where (:status is null or c.status = :status) and c.type =:type

and it is equivalent to:

sql.append(" where ");
if(status != null){
  sql.append(" c.status = :status and ");
}
sql.append(" c.type =:type ");

Answer 4

Here is the solution I found on Hibernate 4.1.9. I had to pass a parameter to my query that can have value NULL sometimes. So I passed the using:

setParameter("orderItemId", orderItemId, new LongType())

After that, I use the following where clause in my query:

where ((:orderItemId is null) OR (orderItem.id != :orderItemId))

As you can see, I am using the Query.setParameter(String, Object, Type) method, where I couldn't use the Hibernate.LONG that I found in the documentation (probably that was on older versions). For a full set of options of type parameter, check the list of implementation class of org.hibernate.type.Type interface.

Hope this helps!

Answer 5

this seems to work as wel ->

@Override
public List<SomeObject> findAllForThisSpecificThing(String thing) {
    final Query query = entityManager.createQuery(
            "from " + getDomain().getSimpleName() + " t  where t.thing = " + ((thing == null) ? " null" : " :thing"));
    if (thing != null) {
        query.setParameter("thing", thing);
    }
    return query.getResultList();
}

Btw, I'm pretty new at this, so if for any reason this isn't a good idea, let me know. Thanks.

Answer 6

1. I believe hibernate first translates your HQL query to SQL and only after that it tries to bind your parameters. Which means that it won't be able to rewrite query from param = ? to param is null.

2. Try using Criteria api:

   Criteria c = session.createCriteria(CountryDTO.class);
   c.add(Restrictions.eq("type", type));
   c.add(status == null ? Restrictions.isNull("status") : Restrictions.eq("status", status));
   List result = c.list();