How to use GeoJSONPointTypeData with Strawberryshake (or any scalar representing an array)

[RobTF]

Hi,

I'm trying to use the spatial stuff with StrawberryShake (SS). The Position scalar is defined as so

"""
A position is an array of numbers. There MUST be two or more elements. The first two elements are longitude and latitude, or easting and northing, precisely in that order and using decimal numbers. Altitude or elevation MAY be included as an optional third element.
"""
scalar Position

As I understand it, SS has a list of scalars it supports natively and any others must be added manually. Therefore I did the following;

in schema.extensions.graphql:

extend scalar Position
    @serializationType(name: "global::System.Text.Json.JsonElement")
    @runtimeType(name: "global::System.Double[]")

and in a .cs code file;

public class PositionSerializer : ScalarSerializer<double[]>
{
    public PositionSerializer() : base("Position")
    {
    }
}

However, this results in SS generating invalid code; note the ! characters in odd places and the array braces in a method name.

        private global::ShakeIt.GraphQL.State.GeoJSONPointTypeData Deserialize_NonNullableIAddIncident_Node_Incident_Location(global::System.Text.Json.JsonElement? obj)
        {
            if (!obj.HasValue)
            {
                throw new global::System.ArgumentNullException();
            }

            var typename = obj.Value.GetProperty("__typename").GetString();
            if (typename?.Equals("GeoJSONPointType", global::System.StringComparison.Ordinal) ?? false)
            {
                return new global::ShakeIt.GraphQL.State.GeoJSONPointTypeData(typename, coordinates: Deserialize_Double[](global::StrawberryShake.Json.JsonElementExtensions.GetPropertyOrNull(obj, "coordinates")));
            }

            throw new global::System.NotSupportedException();
        }

        private global::System.Double[]? Deserialize_Double[](global::System.Text.Json.JsonElement? obj) { if 
        ( !obj.HasValue ) { return  null ;  } return _positionParser.Parse(obj.Value ! ) ; }

Am I doing this correctly? If not, what am I doing wrong?

thanks!

[RobTF]

Ok, engaging the grey matter I found a solution - simply sidestep the issue by using a custom class which wraps a collection of the value.

e.g.

In some .cs file.

public class Position : Collection<double> { }

public class PositionSerializer : ScalarSerializer<JsonElement, Position>
{
    public PositionSerializer() : base("Position") {}

    public override Position Parse(JsonElement serializedValue)
        => serializedValue.Deserialize<Position>() ?? throw new InvalidOperationException();

    protected override JsonElement Format(Position runtimeValue)
        => System.Text.Json.JsonSerializer.SerializeToElement(runtimeValue);
}

In schema.extensions.graphql

extend scalar Position
    @serializationType(name: "global::System.Text.Json.JsonElement")
    @runtimeType(name: "global::MyApp.Position")

In program startup

serviceCollection
    .AddSerializer<PositionSerializer>()
    .AddTestClient();

Then touch wood, everything seems to work now.

[RobTF]

Possible solution to #3685.