feature: Provide a toEntityList from a set of loaded IDs

[SylvainAssemat]

Hi all

I have a question / use case about the load() query usign some MetamodelField

My goal is to have a model (RDUser in my case) with limited attribute (ID only as shown below)

Is this somtehing possible to have a kind of conversion based on MetamodelField in entry, and a List at the end ?

This work

            SearchStream<RDUser> searchStream = entityStream.of(RDUser.class);
            List<Single<String>> list = searchStream
                    //.filter(predicate)
                    //.sorted(comparator)
                    //.skip(pageable.getPageNumber() * pageable.getPageSize())
                    //.limit(pageable.getPageSize())
                    .load(RDUser$.ID)
                    .toList(String.class);

This is not working

  SearchStream<RDUser> searchStream = entityStream.of(RDUser.class);
            Page<RDUser> list = searchStream
                    //.filter(predicate)
                    //.sorted(comparator)
                    //.skip(pageable.getPageNumber() * pageable.getPageSize())
                    //.limit(pageable.getPageSize())
                    .load(RDUser$.ID)
                    .toList(PageRequest.ofSize(50000), RDUser.class);

Exception :

log.info("-> " + list.getContent());

java.lang.NullPointerException: Cannot invoke "Object.toString()" because the return value of "java.util.Map.get(Object)" is null

 AggregationStream<RDUser> aggregationStream = searchStream
                    //.filter(predicate)
                    //.sorted(comparator)
                    //.skip(pageable.getPageNumber() * pageable.getPageSize())
                    //.limit(pageable.getPageSize())
                    .load(RDUser$.ID);

            aggregationStream.aggregate().getResults().stream().forEach(System.out::println);

{id=020cc931-954b-4b42-83c3-49489945ca72}
{id=031dd63d-87c1-4c17-9552-af8d38a4630e}
{id=1780534c-d47b-473c-be92-37dd1342c001}
{id=1f0d13d7-452d-442e-8a7e-5bf384dde960}
{id=2e833aff-0734-4b69-9000-d0e3400ebedd}
{id=46bc80af-ef55-46dd-b890-4e78ae9e0c46}
{id=48edcd36-df7e-44c2-9521-6824104f4e51}
{id=52837167-894a-4542-8468-2f1f97aa857f}
{id=71b478c8-044a-4eb7-8445-0f24d175e209}
{id=83e5e31d-234b-4fb9-b17f-d58f28c5b22f}
{id=9962907a-ec4c-41cc-9902-810d94f3bd32}
{id=ae8e15a2-5940-4dcc-8815-5695d4f8e77f}

This function seems to be the culprit

 @SuppressWarnings("unchecked")
  List<E> toEntityList(AggregationResult aggregationResult) {
    if (isDocument) {
      return aggregationResult.getResults().stream().map(d -> gson.fromJson(d.get("$").toString(), entityClass))
          .toList();
    } else {
      return aggregationResult.getResults().stream()
          .map(h -> (E) ObjectUtils.mapToObject(h, entityClass, mappingConverter)).toList();
    }
  }

Workaround :

//https://github.com/redis/redis-om-spring/issues/474
// @Autowired
// @Qualifier("omGsonBuilder")
// private GsonBuilder gsonBuilder;
Gson gson = gsonBuilder.create(); //Not use jackson

List<RDUser> listRDUser = aggregationStream.aggregate().getResults().stream().map(d -> gson.fromJson(d.toString(), RDUser.class)).toList();

[bsbodden]

Is RDUser annotated with RedisHash or Document? And to be clear you think this happens in toEntityList when it takes the branch that runs return aggregationResult.getResults().stream().map(h -> (E) ObjectUtils.mapToObject(h, entityClass, mappingConverter)).toList();
Based on that, I'm assuming this is RedisHash annotated entity? For RedisHash we delegate the hydration of the object to the mapping converter which is just an extension of the converter from Spring Data Redis.
In the aggregation, once you call load you have an aggregation results that contains only a String (RDUser$.ID). There is not registered converter to convert a single String to an Object. Gson just happens to be smart enough to handle this case.
A better solution might be to provide a .toEntityList(...) method to explicitly force this behavior.

@raphaeldelio @foogaro thoughts?

[foogaro]

@SylvainAssemat if I understand correctly, you have a bunch of RDUser objects saved in Redis, where "all" fields have a value.

Now, through the load method you want to specify which fields need to be populated when retrieving the object from Redis.

Am I understanding correctly?

[SylvainAssemat]

@foogaro Yes that 's what i though it should be possible to do

To get a "light" object, specifying only attributes needed