Unable to locate appropriate constructor

[timowest]

Hello,

I want to write a query in jpa criteriaquery. Here is the query:

SELECT node.category_name, (COUNT(parent.category_name) - 1) AS depth
FROM category_subcategories AS node,
category_subcategories AS parent
WHERE node.lft BETWEEN parent.lft AND parent.rgt
AND node.category_name = 'PORTABLE ELECTRONICS'
GROUP BY node.category_name
ORDER BY node.lft

Here is the code I come up with:

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<CategorySubcategories> cq = cb.createQuery( CategorySubcategories.class );
Root<CategorySubcategories> node = cq.from( CategorySubcategories.class );
Root<CategorySubcategories> parent = cq.from( CategorySubcategories.class );
Predicate p1 = cb.equal(node.get("categoryName"), categoryName);
Predicate p2 = cb.between(node.get("lft").as(Integer.class), parent.get("lft").as(Integer.class), parent.get("rgt").as(Integer.class));
Order nodeLft = cb.asc(node.get("lft"));
cq.multiselect(node.get("categoryName"), cb.count(parent.get("categoryName")))
.where(p1, p2)
.groupBy(node.get("categoryName"))
.orderBy(nodeLft);

return em.createQuery(cq).getResultList();

When I execue the test, it shown the following error:

Testcase: testDepthOfSubtree(au.com.houseware.server.ejb.entity.facade.CategorySubcategoriesFacadeTest): Caused an ERROR
org.hibernate.hql.ast.QuerySyntaxException: Unable to locate appropriate constructor on class [au.com.houseware.server.ejb.entity.CategorySubcategories] [select new au.com.houseware.server.ejb.entity.CategorySubcategories(generatedAlias0.categoryName, count(generatedAlias1.categoryName)) from au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias0, au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias1 where ( generatedAlias0.categoryName=:param0 ) and ( generatedAlias0.lft between generatedAlias1.lft and generatedAlias1.rgt ) group by generatedAlias0.categoryName]
java.lang.IllegalArgumentException: org.hibernate.hql.ast.QuerySyntaxException: Unable to locate appropriate constructor on class [au.com.houseware.server.ejb.entity.CategorySubcategories] [select new au.com.houseware.server.ejb.entity.CategorySubcategories(generatedAlias0.categoryName, count(generatedAlias1.categoryName)) from au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias0, au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias1 where ( generatedAlias0.categoryName=:param0 ) and ( generatedAlias0.lft between generatedAlias1.lft and generatedAlias1.rgt ) group by generatedAlias0.categoryName]
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1201)
at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1147)
at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:324)
at org.hibernate.ejb.criteria.CriteriaQueryCompiler.compile(CriteriaQueryCompiler.java:227)
at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:441)
at au.com.houseware.server.ejb.entity.facade.CategorySubcategoriesFacadeMock.findDepthOfSubtreeBy_categ
oryName(CategorySubcategoriesFacadeMock.java:228)
at au.com.houseware.server.ejb.entity.facade.CategorySubcategoriesFacadeTest.testDepthOfSubtree(Categor
ySubcategoriesFacadeTest.java:44)
Caused by: org.hibernate.hql.ast.QuerySyntaxException: Unable to locate appropriate constructor on class [au.com.houseware.server.ejb.entity.CategorySubcategories] [select new au.com.houseware.server.ejb.entity.CategorySubcategories(generatedAlias0.categoryName, count(generatedAlias1.categoryName)) from au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias0, au.com.houseware.server.ejb.entity.CategorySubcategories as generatedAlias1 where ( generatedAlias0.categoryName=:param0 ) and ( generatedAlias0.lft between generatedAlias1.lft and generatedAlias1.rgt ) group by generatedAlias0.categoryName]
at org.hibernate.hql.ast.QuerySyntaxException.convert(QuerySyntaxException.java:54)
at org.hibernate.hql.ast.QuerySyntaxException.convert(QuerySyntaxException.java:47)
at org.hibernate.hql.ast.ErrorCounter.throwQueryException(ErrorCounter.java:82)
at org.hibernate.hql.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:261)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:185)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:136)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:101)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:80)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:124)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:156)
at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:135)
at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1770)
at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:306)

What is wrong with my criteriaQuery?

Any suggestion is very much appreciated.

Thanks
Sam

timowest

We don't provide JPA criteria support here, but if you want, I can help you with the transition to Querydsl.

On a second look it looks like you use the projection wrong. Either use


CriteriaQuery<Object[]> cq = cb.createQuery( Object[].class );


or make sure that your projection class a proper constructor which takes the arguments of multiselect.

The Querydsl query would be something like this


QCategorySubcategories node = new QCategorySubcategories("node");
QCategorySubcategories parent = new QCategorySubcategories("parent");
query.from(node, parent)
    .where(
        node.categoryName.eq(categoryName),
        node.lft.between(parent.lft, parent.rgt))
    .groupBy(node.categoryName)
    .orderBy(node.lft.asc())
    .list(node.categoryName, parent.categoryName.count())