[hibernate-dev] Stream result change proposal

[Vlad Mihalcea]

To get a picture of why we need this, consider the following example from
the docs:

Stream<Object[]> persons = session.createQuery(
   "select p " +
   "from Person p " +
   "where p.name like :name" )
.setParameter( "name", "J%" )
.stream();

Map<Phone, List<Call>> callRegistry = persons
   .map( row -> Person.class.cast( row[0] ) )
   .flatMap( person -> person.getPhones().stream() )
   .flatMap( phone -> phone.getCalls().stream() )
   .collect(Collectors.groupingBy(Call::getPhone));


The .map( row -> Person.class.cast( row[0] ) ) call should be avoided and
we should return a Stream<Person> in this case.

Vlad

On Tue, Jun 7, 2016 at 12:50 PM, Vlad Mihalcea <mihalcea.vlad at gmail.com>
wrote:

> Hi,
>
> While writing documentation for the new 5.2 Query.stream() API, I realized
> that we don't return a Stream<T>, but a Stream<Object[]> which could
> confuse users.
> This is because ScrollableResultsImpl does something like this:
>
> if ( result != null && result.getClass().isArray() ) {
>    currentRow = (Object[]) result;
> }
> else {
>    currentRow = new Object[] {result};
> }
>
> The result is the actual entity that we queries, while the currentRow is an Object[].
>
> I think we might want to change the stream result so that we return the result for each available entry.
>
> Vlad
>