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ClassCastException when using nested MappingProjection with single Expression #295

Kwaq opened this Issue Nov 28, 2012 · 1 comment


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Kwaq commented Nov 28, 2012

Version: 2.9.0

I'm getting this exception:

java.lang.ClassCastException: java.lang.String cannot be cast to com.example.ResultPart
    at com.example.MappingTest$
    at com.example.MappingTest$
    at com.mysema.query.types.MappingProjection.newInstance(
    at com.mysema.query.types.FactoryExpressionUtils$FactoryExpressionAdapter.newInstance(
    at com.mysema.query.jpa.hibernate.FactoryExpressionTransformer.transformTuple(
    at org.hibernate.hql.HolderInstantiator.instantiate(
    at org.hibernate.loader.hql.QueryLoader.getResultList(
    at org.hibernate.loader.Loader.listIgnoreQueryCache(
    at org.hibernate.loader.Loader.list(
    at org.hibernate.loader.hql.QueryLoader.list(
    at org.hibernate.hql.ast.QueryTranslatorImpl.list(
    at org.hibernate.engine.query.HQLQueryPlan.performList(
    at org.hibernate.impl.SessionImpl.list(
    at org.hibernate.impl.QueryImpl.list(
    at org.hibernate.ejb.QueryImpl.getResultList(
    at com.mysema.query.jpa.impl.AbstractJPAQuery.getResultList(
    at com.mysema.query.jpa.impl.AbstractJPAQuery.list(

Executing following code

        final JPAQuery query = new JPAQuery(entityManager);

        final QSomeEntity ent = QSomeEntity.someEntity;
        final MappingProjection<ResultPart> key = new MappingProjection<ResultPart>(ResultPart.class,
            ent.firstProperty) {

            protected ResultPart map(final Tuple row) {
                return new ResultPart();

        final List<ResultObject> list = query.from(ent).list(
            new MappingProjection<ResultObject>(ResultObject.class, key) {

                protected ResultObject map(final Tuple row) {
                    final ResultPart consolidationKey = row.get(key);
                    return new ResultObject();

Changing key projection declaration to

        final MappingProjection<ResultPart> key = new MappingProjection<ResultPart>(ResultPart.class,
            ent.firstProperty, ent.secondProperty) {

            protected ResultPart map(final Tuple row) {
                return new ResultPart();


As You notice, the only difference is that in second case I pass two expressions to MappingProjection constructor.
I don't fill result objects because it is irrelevant. ResultPart is supposed to be part of the ResultObject.

timowest added a commit that referenced this issue Nov 28, 2012


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timowest Jan 13, 2013


Released in 3.0.0.BETA1


timowest commented Jan 13, 2013

Released in 3.0.0.BETA1

@timowest timowest closed this Jan 13, 2013

timowest added a commit that referenced this issue Apr 19, 2013

@timowest timowest added this to the 3.0.0 milestone Apr 14, 2014

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