Cannot cast javax.persistence.Query to QueryImpl?

michaelchan0427 · **Joined:** Mon Apr 04, 2011 6:37 am **Posts:** 4

Hi All,

My first post here.

I am a newbie and have ran into a Class Cast Exception when attempting to cast javax.persistence.Query to org.hibernate.ejb.QueryImpl.

And apparently Query is an instance of QueryImpl??

Code:

javax.persistence.Query query = em.createQuery(SOME_QUERY);
    
org.hibernate.ejb.QueryImpl qi = (org.hibernate.ejb.QueryImpl)query;

I am getting the following exception

Code:

java.lang.ClassCastException: $Proxy34 cannot be cast to org.hibernate.ejb.QueryImpl

What am I doing wrong? I am hoping to get some advice, thanks!

pasha · **Joined:** Sat Nov 27, 2004 4:13 am **Posts:** 137

According to your exception, your query variable is a dynamic proxy which implements the interface, and it is not a direct implementation of org.hibernate.ejb.QueryImpl, and who knows maybe it delegates most of method implementations to a org.hibernate.ejb.QueryImpl or maybe a org.hibernate.impl.QueryImpl

michaelchan0427 · **Joined:** Mon Apr 04, 2011 6:37 am **Posts:** 4

Hi, thanks for the reply.

I checked in the Eclipse debugger that it is an instance of org.hibernate.ejb.QueryImpl.

This seems to be related to target class proxying.

http://static.springsource.org/spring/d ... p-api.html

niks23 · **Joined:** Mon Apr 04, 2011 3:31 am **Posts:** 41

hey try this

import org.hibernate.Query;

private Transaction tx = null;
private Session session = null;

public Admin verifyLogin(String userId, String userPass) throws Exception
{
try
{
session = HibernateUtil.getSession();
tx = session.beginTransaction();
Query q = session.createQuery("from Admin where userId =:userId AND userPass = :userPass );
q.setString("userId", userId);
q.setString("userPass", userPass);
Admin result = (Admin) q.uniqueResult();
tx.commit();
return result;
}
catch (HibernateException e)
{
tx.rollback();
System.err.println("Error-> " + e);
throw new Exception("Failed at trying to get session");
}
}

here Admin is nothing but the hibernet class name
db having admin table

sanne.grinovero · **Posted:** Thu Apr 07, 2011 2:17 pm

you shouldn't need the QueryImpl. what are you trying to do?

michaelchan0427 · **Joined:** Mon Apr 04, 2011 6:37 am **Posts:** 4

s.grinovero wrote:

you shouldn't need the QueryImpl. what are you trying to do?

Hi Sanne, thanks for the reply. This is a really good question!

I was trying a HQL query with IN clause and query.setParameter(String string, Object value), see the example below:

I have the following query:

Code:

select prod from Product as prod where prod.categories IN (:cat)

In the Product bean, I have the following annotation mapping:

Code:

@ManyToMany(targetEntity=Category.class,fetch = FetchType.LAZY)
@JoinTable(
            name="CATEGORYPRODUCTREL",
            joinColumns=@JoinColumn(name="PRODPK"),
            inverseJoinColumns=@JoinColumn(name="CATPK")
)
@Cascade({CascadeType.REFRESH, CascadeType.PERSIST, CascadeType.SAVE_UPDATE, CascadeType.MERGE})
public Set<Category> getCategories() {
.....
}

When I use the HQL above, I get something like a SQL Gramma Exception.

But then I found this:

http://opensource.atlassian.com/project ... e/HHH-5126

So I upgraded Hibernate core and entity manager to the latest version and everything's fine now.

Thanks!

michaelchan0427 · **Joined:** Mon Apr 04, 2011 6:37 am **Posts:** 4

Just want to follow up on this, I executed the following using entity manager:

Code:

Query query = em.createQuery("SELECT count(p.pk) from Product as p where p.categories IN :cat");
query.setParameter("cat", category);

And I was getting SQL grammar exception, the SQL query was:

Code:

Hibernate: select count(product0_.PK) as col_0_0_ from PRODUCT product0_ cross join CATEGORYPRODUCTREL categories1_, CATEGORY category2_ where product0_.PK=categories1_.PRODPK and categories1_.CATPK=category2_.PK and (. in (?))

Category and product has a many to many relationship.

Can anyone help?

sanne.grinovero · **Posted:** Wed Apr 13, 2011 7:07 pm

please start new threads for new questions.
The "in" operator expects a single object to be present in a collection. so it should be like "p.category in (:categories)" : the other way around.