Problem with "select new" HQL clause

stolley · **Posted:** Wed Dec 17, 2003 1:55 am

Folks,

When my DTO object that I am "Select new"'ing into has a constructor that takes native types, I get the error attached.

If my DTO has a ctor which takes wrapper types, the code works.

If it has both, then Hibernate seems to prefer the native version, and I get the error.

I tried implementing the native-type ctor in two ways, using the "this" keyword to delegate to the wrapper-type ctor or with direct calls to the setter methods on the DTO. Didn't seem to make any difference.

I'm using nightly build 20031214.

Is this worth creating a JIRA issue for?

Code:

    [junit] Testcase: testFindDocumentsByCaseDTOsWithEmptyCriteria(nrm.clas.persistence.document.test.DocumentPersistenceManagerTest):  Caused an ERROR
    [junit] Error finding documents by case
    [junit] nrm.clas.persistence.PersistenceLayerException: Error finding documents by case
    [junit]     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    [junit]     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    [junit]     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    [junit]     at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
    [junit]     at nrm.clas.ExceptionUtil.instantiateException(ExceptionUtil.java:89)
    [junit]     at nrm.clas.ExceptionUtil.createNestedException(ExceptionUtil.java:127)
    [junit]     at nrm.clas.ExceptionUtil.createPersistenceLayerException(ExceptionUtil.java:312)
    [junit]     at nrm.clas.ExceptionUtil.createPersistenceLayerException(ExceptionUtil.java:291)
    [junit]     at nrm.clas.persistence.document.DocumentPersistenceManagerImpl.findDocumentsByCaseDTOs(DocumentPersistenceManagerImpl.java:162)
    [junit]     at nrm.clas.persistence.document.test.DocumentPersistenceManagerTest.testFindDocumentsByCaseDTOsWithEmptyCriteria(DocumentPersistenceManagerTest.java:45)
    [junit]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    [junit]     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    [junit]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    [junit]     at nrm.clas.test.ClasTestCase.run(ClasTestCase.java:508)
    [junit] Caused by: nrm.clas.common.persistence.PersistenceException: find
    [junit]     at nrm.clas.persistence.BasePersistenceManagerImpl.handleError(BasePersistenceManagerImpl.java:97)
    [junit]     at nrm.clas.persistence.BasePersistenceManagerImpl.handleError(BasePersistenceManagerImpl.java:116)
    [junit]     at nrm.clas.persistence.BasePersistenceManagerImpl.find(BasePersistenceManagerImpl.java:365)
    [junit]     at nrm.clas.persistence.document.DocumentPersistenceManagerImpl.findDocumentsByCaseDTOs(DocumentPersistenceManagerImpl.java:159)
    [junit]     ... 16 more
    [junit] Caused by: net.sf.hibernate.QueryException: could not instantiate: class nrm.clas.dto.document.CaseDocumentDTO
    [junit]     at net.sf.hibernate.hql.QueryTranslator.getResultColumnOrRow(QueryTranslator.java:993)
    [junit]     at net.sf.hibernate.loader.Loader.doQuery(Loader.java:221)
    [junit]     at net.sf.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:132)
    [junit]     at net.sf.hibernate.loader.Loader.doList(Loader.java:949)
    [junit]     at net.sf.hibernate.loader.Loader.list(Loader.java:940)
    [junit]     at net.sf.hibernate.hql.QueryTranslator.list(QueryTranslator.java:833)
    [junit]     at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1475)
    [junit]     at net.sf.hibernate.impl.SessionImpl.find(SessionImpl.java:1454)
    [junit]     at nrm.clas.persistence.BasePersistenceManagerImpl.find(BasePersistenceManagerImpl.java:359)
    [junit]     ... 17 more
    [junit] Caused by: java.lang.NullPointerException
    [junit]     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    [junit]     at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    [junit]     at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    [junit]     at java.lang.reflect.Constructor.newInstance(Constructor.java:274)
    [junit]     at net.sf.hibernate.hql.QueryTranslator.getResultColumnOrRow(QueryTranslator.java:990)
    [junit]     ... 25 more

david · **Posted:** Wed Dec 17, 2003 9:12 pm

It is a know limitation, have a look throuhg JIRA to see if you can find an entry if not yes create one so its documented.

stolley · **Posted:** Wed Dec 17, 2003 9:39 pm

Couldn't find anything, so I raised HB-567.

alvim · **Posted:** Mon Jan 05, 2004 2:43 pm

Hi!

Any news here? We have the same problem...

Thanks a lot

Paulo Alvim - Powerlogic - Brazil

stolley · **Posted:** Mon Jan 05, 2004 6:52 pm

It's caused by having null values in the result set.
Obviously (now, anyway :), you can't send a null reference to a constructor parameter that takes a primitive type.

So if one of the columns that you are querying is declared not-null and the query does nothing to stop null values in the result set for that column, then you'll be asking Hibernate to put null into this primitive value, which the language itself (never mind Hibernate) can't do.

If you need to be able to support null values in this situation then you'll need to use a ctor that takes a wrapper class instead.

alvim · **Posted:** Wed Jan 07, 2004 5:31 pm

Thank you, Stolley!...

I did know about the cause (null value to primitive...) but your information about the "ctor that takes a wrapper class instead." is very interesting. Is there any link that explain how to do that?

Alvim.

stolley · **Posted:** Wed Jan 07, 2004 7:46 pm

What I mean is, if you have a ctor like this:

public SomeObject(long id, String value1, boolean value2){
this.id = new Long(id);
this.value1 = value1;
this.value2 = new Boolean(value2);
}

Change it to (you have to change it, or hibernate will choose the primitive version in preference):

public SomeObject(Long id, String value1, Boolean value2){
this.id = id;
this.value1 = value1;
this.value2 = value2;
}

alvim · **Posted:** Thu Jan 08, 2004 1:01 pm

Ok! Now I undestand that "ctor" is "creator"! I'm sorry I didn't know this word...

This would be the ideal. But I'm using 2.03 and Hibernate seems to try always "long" instead of recognize the wrapper "Long" in the ctor. Would it possible be a bug of this version? Or do I have to make anything else (I tried to put "java.lang.Long" in the mapping "type" attribute but it did't work yet)

Thanks once more...

stolley · **Posted:** Thu Jan 08, 2004 6:58 pm

ctor is my shorthand for constructor, yeah.

The patch to allow this functionality was only applied for HB 2.1 and later, previous versions could only use constructors that took primitive types.

Issue 97 is the relevant enhancement, you could apply it your copy directly if you can't upgrade to 2.1 for some reason.

http://opensource.atlassian.com/project ... ?key=HB-97

alvim · **Posted:** Fri Jan 09, 2004 7:53 am

Sorry,

I'd like to say "constructor" instead of "creator"...

Thank you very much! This last reply is exactly what I was looking for.:-)