[StrawberryShake] Custom scalar (non-null reference type) fails client to build when used as Input Type

[Arsync]

I have project with Non-Null Reference Types option enabled (important note) and NodaTime referenced on client side.

In schema.extensions.graphql:

directive @serializationType(name: String!) on SCALAR
directive @runtimeType(name: String!) on SCALAR

extend scalar LocalDate
    @serializationType(name: "System.String")
    @runtimeType(name: "NodaTime.LocalDate")

Serializer:

public class LocalDateSerializer : ScalarSerializer<string, LocalDate>
{
    public LocalDateSerializer() : base(nameof(LocalDate)) { }

    public override LocalDate Parse(string serializedValue)
    {
        var parseResult = LocalDatePattern.Iso.Parse(serializedValue);

        if (!parseResult.Success)
            throw parseResult.Exception;

        return parseResult.Value;
    }

    protected override string Format(LocalDate runtimeValue)
    {
        return runtimeValue.ToString("R", CultureInfo.InvariantCulture);
    }
}

Query looks like

query findMyAppointments($pointDate: LocalDate!)
{
  findMyAppointments(pointDate: $pointDate)
  {
    id
  }
}

And there is error in generated client:
CS0037 Cannot convert null to 'LocalDate' because it is a non-nullable value type

Generated fragment:

private global::System.Object? FormatPointDate(global::NodaTime.LocalDate value)
{
    // This line fails project build: non-nullable type tries to check for null
    if (value is null)
    {
        throw new global::System.ArgumentNullException(nameof(value));
    }

    return _localDateFormatter.Format(value);
}

How to resolve this?

StrawberryShake.Blazor version 13.0.5
.NET 7.0

[david-driscoll]

I am also running into this same problem 😢

[david-driscoll]

I believe I've found a workaround, though this should be documented imo.

Change
directive @runtimeType(name: String!) on SCALAR
to
directive @runtimeType(name: String!, valueType: Boolean) on SCALAR

And then define your types as like

extend scalar DateTimeZone
    @serializationType(name: "global::System.String")
    @runtimeType(name: "global::NodaTime.DateTimeZone", valueType: true)
extend scalar Duration
    @serializationType(name: "global::System.String")
    @runtimeType(name: "global::NodaTime.Duration", valueType: true)
extend scalar Instant
    @serializationType(name: "global::System.String")
    @runtimeType(name: "global::NodaTime.Instant", valueType: true)

This seems to be working for me so far.