Date and Time

Huml.Net serialises and deserialises DateTime, DateTimeOffset, TimeSpan, DateOnly, and TimeOnly natively as quoted ISO-8601 / canonical strings. No custom converter is required.

Supported Types

Type	Format	Example	Availability
`DateTime`	`"O"`	`"2026-05-19T14:30:00.0000000"`	All TFMs
`DateTimeOffset`	`"O"`	`"2026-05-19T14:30:00.0000000+01:00"`	All TFMs
`TimeSpan`	`"c"`	`"1.02:03:04"`	All TFMs
`DateOnly`	`yyyy-MM-dd`	`"2026-05-19"`	.NET 6 and later
`TimeOnly`	`HH:mm:ss.FFFFFFF`	`"14:30:00"`	.NET 6 and later

All five types serialise as quoted HUML string scalars and deserialise back with full fidelity.

Usage

using Huml.Net;

public class Event
{
    public string Name { get; set; } = string.Empty;
    public DateTime OccurredAt { get; set; }
    public TimeSpan Duration { get; set; }
}

var ev = HumlSerializer.Deserialize<Event>("""
    %HUML v0.2.0
    Name: "conference"
    OccurredAt: "2026-05-19T09:00:00.0000000"
    Duration: "0.08:00:00"
    """);
// ev.OccurredAt == new DateTime(2026, 5, 19, 9, 0, 0)
// ev.Duration   == TimeSpan.FromHours(8)

DateOnly and TimeOnly

DateOnly and TimeOnly are available on .NET 6 and later only. These types do not exist on netstandard2.1. If your project targets netstandard2.1, use DateTime or a custom converter instead.

using Huml.Net;

public class Schedule
{
    public DateOnly Date { get; set; }
    public TimeOnly StartsAt { get; set; }
}

var schedule = HumlSerializer.Deserialize<Schedule>("""
    %HUML v0.2.0
    Date: "2026-05-19"
    StartsAt: "09:30:00"
    """);
// schedule.Date     == new DateOnly(2026, 5, 19)
// schedule.StartsAt == new TimeOnly(9, 30)

Compatibility

Type	netstandard2.1	.NET 8	.NET 9	.NET 10
`DateTime`	Yes	Yes	Yes	Yes
`DateTimeOffset`	Yes	Yes	Yes	Yes
`TimeSpan`	Yes	Yes	Yes	Yes
`DateOnly`	No	Yes	Yes	Yes
`TimeOnly`	No	Yes	Yes	Yes

Migration Note

Prior to 0.2.0-alpha.2, all five types fell through to the POCO reflection path. DateTime and DateTimeOffset produced incorrect output and DateOnly/TimeOnly would throw InvalidCastException during deserialisation. Any custom converter previously used to work around this can be removed.