Re: [jnosql-dev] Support for iterables #200

[Otávio Gonçalves de Santana <otaviopolianasantana@xxxxxxxxx>]

Ok, I checked several drivers and yes.
Usually, they return as Iterable.
I have on my mind two solutions both it will change the result to all search results.

We can change the result to Iterable itself, e.g.:

Iterable<DocumentEntity> query(String query);

What I propose it to have an interface to represents this result as iterable, therefore:

1. We can have a Stream default method to make easier to the final user.
2. We can create a default supplier where give the entities result from database and a converter, to translate the entities to Jakarta NoSQL API, it will create a default Result to the drives, so make to driver support as well.

import java.util.Objects;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;

public interface Result<T> extends Iterable<T> {

    default Stream<T> toStream() {
        return StreamSupport.stream(this.spliterator(), false);
    }

    static <E, T> Result<T> of(Iterable<E> entities, Function<E, T> converter) {
        Objects.requireNonNull(converter, "converter is required");
        Objects.requireNonNull(entities, "entities is required");
        final ResultSupplier<T, E> supplier = ServiceLoaderProvider.get(ResultSupplier.class);
        return supplier.apply(converter, entities);
    }

    interface ResultSupplier<T, E> extends BiFunction<Function<E, T>, Iterable<E>, Result<T>> {

    }
}

The new return:

Result<DocumentEntity> query(String query);

So:

   //database provider side
  Iterable<DatabaseEntity> entities = ...;//native query
  Function<DatabaseEntity, ColumnEntity> converter = ...;//the translate logic
  final Result<ColumnEntity> result = Result.of(entities, converter);//return this value to the user

  //lazy value
  for (ColumnEntity columnEntity : result) {
       System.out.println("");
  }
  //return as Stream
  final Stream<ColumnEntity> columnEntityStream = result.toStream();

On Sat, Aug 17, 2019 at 6:05 AM Otávio Gonçalves de Santana <otaviopolianasantana@xxxxxxxxx> wrote:

It’s been on my mental back-burner to try out some lazy-loading options in my driver. I’ve considered if it’d work to make a List implementation that lazy-loads internally, since that’d keep some handy methods that Iterable doesn’t have. On the other hand, maybe Stream would be most idiomatic now, and could have efficient count, etc. operations while also having a stronger implication of lazy-loading.

-Jesse

On Fri, Aug 16, 2019 at 10:35 PM Otávio Gonçalves de Santana <otaviopolianasantana@xxxxxxxxx> wrote:

DocumentCollectionManager::search produces a list.
Do we assume that result will always comfortably fit in memory?
In NoSQL world, it often doesn't and this prevents the whole (very convenient) API to be used at all.

We need a separate search implementation that returns an iterable, or a stream, or an observable

This would be easy to create from existing search implementation. Looking at drivers, most of the time it does iterable -> stream(iterable).collect(toList)

Suggestions?

Ref: https://github.com/eclipse/jnosql/issues/200

--

Otávio Gonçalves de Santana

twitter: http://twitter.com/otaviojava

site:     http://about.me/otaviojava

--

Otávio Gonçalves de Santana

twitter: http://twitter.com/otaviojava

site:     http://about.me/otaviojava

--

Otávio Gonçalves de Santana

twitter: http://twitter.com/otaviojava

site:     http://about.me/otaviojava