.NET 6 | Support the new BCL DateOnly and TimeOnly structs

[roji]

New DateOnly and TimeOnly structs are being introduced to .NET 6 as alternatives to DateTime (dotnet/runtime#49036). SqlClient and add support for these as perfect mappings for SQL Server date and time.

[Wraith2]

Are they likely to have ADO surface area, e.g. DbDataReader.GetDateOnly etc or do you think that providing only GetFieldValue(Async)<T> is appropriate because that wouldn't need any new methods?

[mattjohnsonpint]

Given that the SQL type is date, I suggest making a method DBDataReader.GetDate even if the type it returns in .NET is called DateOnly (which is still being discussed).

[Wraith2]

@mattjohnsonpint I think that would depend on the ranges supported. If it maps directly then I agree if there are any differences we may want to call out the DataOnly type is not the same as sql DATE. Mapping for clr to sql types is already complicated and a bit messy imo I think we should take care not to make it worse for the save of brevity.

[mattjohnsonpint]

They have the exact same range and precision.

[cheenamalhotra]

Acknowledged.
Looking forward to solidification in design.

[roji]

Are they likely to have ADO surface area, e.g. DbDataReader.GetDateOnly etc or do you think that providing only GetFieldValue(Async) is appropriate because that wouldn't need any new methods?

I'm not aware of a reason to add new GetDate/GetTime APIs to DbDataReader - the generic GetFieldValue (and Async) should be sufficient for retrieving the new types (unless you guys have a reason?).

[mattjohnsonpint]

No strong opinions here, but a reason would be discoverability for those used to APIs like DbDataReader.GetDateTime.

[roji]

No strong opinions here, but a reason would be discoverability for those used to APIs like DbDataReader.GetDateTime.

That's true, but don't think it's sufficient... Note how there are no async equivalents for the Get* methods (e.g. no GetDateTimeAsync), and users must use the generic GetFieldValueAsync. Basically I think the Get* methods are a bit of a remnant from the days before generics existed.

[mattjohnsonpint]

Please note that the final names for these types are DateOnly and TimeOnly and that they are now merged into the main branch for the next version of .NET 6 (preview 4 likely). Please rename the title of this issue accordingly. Thanks.