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viliam.durina
 Post subject: ClassCastException with SQLQuery and setCacheable(true)
PostPosted: Tue Jul 22, 2008 8:12 am 
Newbie

Joined: Tue Jul 08, 2008 8:02 am
Posts: 10
I have the following code:

Code:
   SQLQuery sqlQuery = s.createSQLQuery("select 1");
   sqlQuery.setCacheable(true);
   Number num = (Number) sqlQuery.uniqueResult();


But I get the following exception:
Code:
Caused by: java.lang.ClassCastException: java.lang.Integer
   at org.hibernate.cache.StandardQueryCache.put(StandardQueryCache.java:83)
   at org.hibernate.loader.Loader.putResultInQueryCache(Loader.java:2187)
   at org.hibernate.loader.Loader.listUsingQueryCache(Loader.java:2138)
   at org.hibernate.loader.Loader.list(Loader.java:2096)
   at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
   at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1697)
   at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
   at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152)
   at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:811)
   at myClass.myMethod(MyClass.java:53)


I think it is a bug, but maybe I'm wrong. The code in StandardQueryCache.put() checks for returnTypes.length, and if it other than 1, it casts to Object[], and this causes the error. The returnTypes.length in this case is 0.

Thanks,
Viliam
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jadam
 Post subject:
PostPosted: Tue Jul 22, 2008 4:34 pm 
Newbie

Joined: Mon Apr 21, 2008 5:07 pm
Posts: 6
hi Viliam

you got a
Code:
java.lang.ClassCastException: java.lang.Integer
.
Maybe you shouldn't use a Number cast but instead of that an Integer?
If this doesn't help just try to use something in that way

Code:
Object num = (Object) sqlQuery.uniqueResult();
if(num instanceof Integer){
  int value = ((Integer) num).intValue();
  System.out.println("Instance is an Integer and the int representation is "+value);
}
if(num instanceof Integer){
  int value = ((Integer) num).intValue();
  System.out.println("Instance is an Integer and the int representation is "+value);
}
if(num instanceof Double){
  double value = ((Double) num).doubleValue();
  System.out.println("Instance is a Double and the double representation is "+value);
}


Are you using J2SE5.0? If so then Number is an abstract class.

Hope it helps
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viliam.durina
 Post subject:
PostPosted: Wed Jul 23, 2008 12:52 am 
Newbie

Joined: Tue Jul 08, 2008 8:02 am
Posts: 10
The exception occured inside of org.hibernate.cache.StandardQueryCache.put(), not inside of my method. There is a cast that fails, on line 83.

I use java.lang.Number because different databases could return different subclasses of Number (e.g. BigInteger, Long, etc.).

I forgot, I use Hibernate 3.2.4.

Viliam
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jadam
 Post subject:
PostPosted: Thu Jul 24, 2008 6:48 pm 
Newbie

Joined: Mon Apr 21, 2008 5:07 pm
Posts: 6
It seems to be tricky. hope that there is a solution outside. From sure you checked the configuration to be correct? Did you check different cache modes? What happens if you don't user Number but an implementation?
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gabriel_f
 Post subject:
PostPosted: Thu Jan 15, 2009 8:29 am 
Newbie

Joined: Thu Jan 15, 2009 8:19 am
Posts: 1
I got the same error and it was solved by calling addScalar(String, Type) on the query. In my case I had to say that what I was selecting was of type String to get the caching to work. I don't know how to handle the particular case in this thread since addScalar takes a name as the first parameter and the "1" in the query at hand does not have a name.

For my purposes this worked:

Code:
session.createSQLQuery("select name from some_table where name like :prefix")
                        .addScalar("name", Hibernate.STRING)
                        .setString("prefix", prefix + "%")
                        .setCacheable(true)
                        .list();


which I want to return all names with a certain prefix. Without the call to addScalar I got a java.lang.ClassCastException: java.lang.String when cacheable was set to true.

I hope this helps someone that Googles to this page.
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viliam.durina
 Post subject: Re: ClassCastException with SQLQuery and setCacheable(true)
PostPosted: Sat Jun 20, 2009 10:24 am 
Newbie

Joined: Tue Jul 08, 2008 8:02 am
Posts: 10
Thanks, this helped in my case as well...
You can give alias to any column, in this case "select 1 as numberone".

Viliam
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