Question

Trying to create an object from an HQL query, but just can’t figure out what i’m doing wrong.

Query:

String query = "SELECT product.code, SUM(product.price), COUNT(product.code)
from Product AS product
GROUP BY product.code"

(or should I use new MyCustomList(product.code, SUM(… , even though it’s not mapped?)
Now I want to cast this returned list into a similar object:

class MyCustomList{
  public String code;
  public BigDecimal price;
  public int total;

  // Constructor
  public MyCustomList(String code, String price, int total){ //...

Retrieving the data:

// This throws ClassCastException    
List<MyCustomList> list = MyClass.find(query).fetch();

Using Play framework

Answer 1

I think that the section 15.6. The select clause covers what you’re trying to achieve:

15.6. The select clause

…

Queries can return multiple objects
and/or properties as an array of type
Object[]:

select mother, offspr, mate.name
from DomesticCat as mother
    inner join mother.mate as mate
    left outer join mother.kittens as offspr

Or as a List:

select new list(mother, offspr, mate.name)
from DomesticCat as mother
    inner join mother.mate as mate
    left outer join mother.kittens as offspr

Or – assuming that the class Family
has an appropriate constructor – as an
actual typesafe Java object:

select new Family(mother, mate, offspr)
from DomesticCat as mother
    join mother.mate as mate
    left join mother.kittens as offspr

In your case, you probably want:

SELECT new MyCustomList(product.code, SUM(product.price), COUNT(product.code))
from Product AS product
GROUP BY product.code

Where MyCustomList is not necessarily a mapped entity.