Why DateTimeOffset.Date returns DateTime instead of DateTimeOffset?

[christallire]

It needs to be more straightforward. It's not foolproof enough.
I was scratching my head because it changed the variable's timezone unnoticed.

for an example:

        var truncatedDate = DateTimeOffset.UtcNow.Date;
        DateTimeOffset codeUsingDateTimeOffsetSomewhere = truncatedDate;

[Clockwork-Muse]

Because at the time DateTimeOffset was created, the Date class didn't exist yet.

Note that by removing the time information you're also removing anything that would allow you to tie back to a time zone anyhow, so a change in time zone is to be expected.

[colejohnson66]

That’s not the question. Why is a DateTimeOffset property returning something that isn’t a DateTimeOffset?

[Clockwork-Muse]

Because an actual date domain value has neither time nor timezone information, and that's what the property is intended to provide. The best they could do at the time, lacking a date-specific domain type like DateOnly, was use the existing DateTime type, and set a couple of properties so it would be "regionless" (however poorly that works in some situations).

For comparison, the equivalent signature in NodaTime does use a DateOnly equivalent type:

public readonly struct OffsetDateTime {
    ....
    public readonly LocalDate Date { get; }
}