Cannot map nullable types to FlatTableProjections

[nathanjcollins]

When I use a FlatTableProjection, I cannot use non string nullables.

public record ImportFailedWithStringErrorCode(string? ErrorCodeString);

public record ImportFailedWithGuidErrorCode(Guid? ErrorCodeGuid);

public class FlatImportProjection : FlatTableProjection
{
    public FlatImportProjection()
        : base("import_history", SchemaNameSource.EventSchema)
    {
        Table.AddColumn<Guid>("id").AsPrimaryKey();

        TeardownDataOnRebuild = true;

        Project<ImportStarted>(map =>
        {
            map.Map(x => x.Started);
        });

        Project<ImportFailedWithStringErrorCode>(map =>
        {
            map.Map(x => x.ErrorCodeString);
        });

        Project<ImportFailedWithGuidErrorCode>(map =>
        {
            map.Map(x => x.ErrorCodeGuid);
        });
    }
}

If an event of ImportFailedWithGuidErrorCode is created with null, it will fail with the following error:

MessageText: function ms.mt_upsert_import_history_importfailedwithguiderrorcode(uuid, text) does not exist
Hint: No function matches the given name and argument types. You might need to add explicit type casts.

ImportFailedWithStringErrorCode works when passing null.

We have also tried other types, but it only seems to work with nullable strings.

There is a workaround using raw sql, but it's not ideal:

        ops.QueueSqlCommand(
            $"""
            insert into {TableName} (
                ErrorCodeGuid
            )
            values (
                ?::uuid /* note we have to explicitly cast it to a uuid here */
            )
            """,
            e.Data.ErrorCodeGuid?.ToString()!
        );

[jeremydmiller]

@nathanjcollins This is going to be too involved a change for the next quick release. Maybe later in the week, or feel free to dig into the flat table support to make the generated ADO.Net manipulation code robust enough to handle the nullable types. Or, use a default value for the Guid now.

There's an open branch (https://github.com/JasperFx/marten/tree/flat-table-projections) for reproducing it. I also hit a world of friction on the DateTimeOffset values, but I'm 100% blaming Npgsql for making date time types hard to use in their recent releases.

[nathanjcollins]

@nathanjcollins This is going to be too involved a change for the next quick release. Maybe later in the week, or feel free to dig into the flat table support to make the generated ADO.Net manipulation code robust enough to handle the nullable types. Or, use a default value for the Guid now.

There's an open branch (https://github.com/JasperFx/marten/tree/flat-table-projections) for reproducing it. I also hit a world of friction on the DateTimeOffset values, but I'm 100% blaming Npgsql for making date time types hard to use in their recent releases.

Thanks for taking a look for us, hopefully we'll get some free time to take a look ourselves. But for now we will use the workaround with manual sql queries :)