No implicit conversion from ScoreSort to SortOptions

[MEmanuelsson]

Elastic.Clients.Elasticsearch version:
8.19.6

Elasticsearch version:
8.17.1

.NET runtime version:
9.0.9

Operating system version:
Windows

Description of the problem including expected versus actual behavior:
I'm not sure if this is a bug or if we're doing something wrong but when trying to upgrade from version 8.18.3 to 8.19.6 we're having problem with one final piece of code connected to ScoreSort and SortOptions.

The code we're trying to upgrade looks like this in 8.18.3:

var sortOptions = new List<SortOptions>();
sortOptions.Add(SortOptions.GeoDistance(new GeoDistanceSort
{
    Field = "fieldname",
    Location = [GeoLocation.LatitudeLongitude(new LatLonGeoLocation { Lat = 1.1, Lon = 2.2 })],
    Order = SortOrder.Asc,
    Unit = DistanceUnit.Meters,
    Mode = SortMode.Min
}));
sortOptions.Add(SortOptions.Score(new ScoreSort()));

In 8.19.6 we have this so far but the piece of code we're not sure about how to migrate is connected to the addition of ScoreSort to the list:

var sortOptions = new List<SortOptions>();
sortOptions.Add(new GeoDistanceSort
{
    Field = "fieldname",
    Location = [GeoLocation.LatitudeLongitude(new LatLonGeoLocation { Lat = 1.1, Lon = 2.2 })],
    Order = SortOrder.Asc,
    Unit = DistanceUnit.Meters,
    Mode = SortMode.Min
});
sortOptions.Add(new ScoreSort()); //<-- Does not build

What's the right way to add ScoreSort to the list of SortOptions? Or is this perhaps not necessary, maybe this is added implicitly by Elasticsearch?

Steps to reproduce:

1. Add code above to solution using 8.18.3
2. Upgrade to 8.19.6
3. Code does not build

Expected behavior
Would expect to be able to add ScoreSort like it was possible to do in 8.18.3

[MEmanuelsson]

Realized just a minute after posting this message that this is probably the way to go (stupido me....)

        var sortOptions = new List<SortOptions>();
        sortOptions.Add(new GeoDistanceSort
        {
            Field = "fieldname",
            Location = [GeoLocation.LatitudeLongitude(new LatLonGeoLocation { Lat = 1.1, Lon = 2.2 })],
            Order = SortOrder.Asc,
            Unit = DistanceUnit.Meters,
            Mode = SortMode.Min
        });
        var scoreSortOption = new SortOptions { Score = new ScoreSort() };
        sortOptions.Add(scoreSortOption);

Still, any reason for the implicit operator to not exist in 8.19.6?

[flobernd]

Hi @MEmanuelsson ,

Still, any reason for the implicit operator to not exist in 8.19.6?

Yes. It's a quite unfortunate technical limitation. The SortOptions container supports 5 variants:

1. Doc (type: ScoreSort)
2. Field (type: FieldSort)
3. GeoDistance (type: GeoDistanceSort)
4. Score (type: ScoreSort)
5. Script (type: ScriptSort)

As you can see, Doc and Score both use the ScoreSort type. This causes an ambiguity, because in the implicit conversion operator there is no way we can know which variant is the intended one (aka. should we assign the ScoreSort instance to Doc or rather to Score?).

For this reason, we have to keep the assignment explicit in this case.

Hope that answers your question.