Hey everyone, is there equivalent of `truncatedTo(...

# kotlinx-datetime

[Shervin]

Hey everyone,
is there equivalent of truncatedTo(ChronoUnit.SECONDS) that is present in Java local datetime in KotlinX ?

[Dmitry Khalanskiy [JB]]

Currently, there isn't, we didn't see any significant demand. You're welcome to share your use case: https://github.com/Kotlin/kotlinx-datetime/issues/225!

[Shervin]

Hey @Dmitry Khalanskiy [JB]! thanks for your reply

I'm using Kotlinx to in an 'Interview scheduling system' for which I'd like to set all the meeting share at 0 SECONDS. Hence my need to use truncateTo()

[Dmitry Khalanskiy [JB]]

Where does the data come from that doesn't already have seconds set to zero?

[Shervin]

It's defined by user, from UI input

[Dmitry Khalanskiy [JB]]

Why does the UI input allow times with non-zero seconds if they are ultimately discarded?

[Shervin]

that's beyond my team scope to control, it 's like a common UI component that is used on other teams.

[Dmitry Khalanskiy [JB]]

Got it, thanks!

[Shervin]

what do you think about complexity of adding this?
Is it sth that I can contribute?

[Dmitry Khalanskiy [JB]]

The complexity of this is tiny, here's the whole thing:

public fun LocalTime.truncateTo(unit: DateTimeUnit.TimeBased): LocalTime =
    LocalTime.fromNanosecondOfDay(toNanosecondOfDay().let { it - it % unit.nanoseconds })

public fun LocalDateTime.truncateTo(unit: DateTimeUnit.TimeBased): LocalDateTime =
    LocalDateTime(date, time.truncateTo(unit))

Here are some tests to make sure it works:

@Test
    fun testTruncation() {
        val localTime = LocalTime(1, 2, 3, 456789123)
        assertEquals(LocalTime(1, 2, 3, 456789123), localTime.truncateTo(DateTimeUnit.NANOSECOND))
        assertEquals(LocalTime(1, 2, 3, 456789000), localTime.truncateTo(DateTimeUnit.MICROSECOND))
        assertEquals(LocalTime(1, 2, 3, 456000000), localTime.truncateTo(DateTimeUnit.MILLISECOND))
        assertEquals(LocalTime(1, 2, 3, 0), localTime.truncateTo(DateTimeUnit.SECOND))
        assertEquals(LocalTime(1, 2, 0, 0), localTime.truncateTo(DateTimeUnit.MINUTE))
        assertEquals(LocalTime(1, 0, 0, 0), localTime.truncateTo(DateTimeUnit.HOUR))
    }

The complexity is in making this consistent with the more general request of temporal adjusters: https://github.com/Kotlin/kotlinx-datetime/issues/235 This requires careful considerations and thorough design.

[Shervin]

perfect!
I guess that works for my requirements

[Shervin]

Although I would be happy if I can contribute on this topic if it's needed