Hello, does format ISO8601:2004 is supported ?

# kotlinx-datetime

[Raphael TEYSSANDIER]

Hello, does format ISO8601:2004 is supported ?

[Dmitry Khalanskiy [JB]]

ISO 8601 is a collection of many formats. Some of them are provided by the library, some aren't.

[Raphael TEYSSANDIER]

Is there a list of format supported?

[Dmitry Khalanskiy [JB]]

Nope. Please take a look at the list of classes provided by the library (https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime/): most of them have `parse`/`toString` functions compatible with ISO 8601. Additionally, you can create custom formats (https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime.format/-date-time-format-builder/) to suit your requirements.

[Raphael TEYSSANDIER]

Thanks, to fully understand the InstantIso8601Serializer doesn't support all format of the ISO 8601 ?

[Dmitry Khalanskiy [JB]]

It only supports the extended ISO 8601 format suitable for kotlinx.datetime.Instant. It would be meaningless to try to parse P15DT12H as an Instant (DateTimePeriod should be used for this format); likewise, 2024-01-16 is not an Instant (it's a LocalDate), and neither is something like 2024-10-23T21:59/2025-01-16T12:00 (which is a time interval, we don't provide those, as there doesn't seem to be any demand).

[Dmitry Khalanskiy [JB]]

Also, there isn't a lot of sense in explicitly specifying `InstantIso8601Serializer`: Instant is @Serializable by default, and it uses the ISO 8601 strings as the format. Please see https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime.format[…]omponents/-formats/-i-s-o_-d-a-t-e_-t-i-m-e_-o-f-f-s-e-t.html

[Raphael TEYSSANDIER]

I was searching for format without a year like --01-13T12:00 . Thank you very much

[Dmitry Khalanskiy [JB]]

It's not provided out of the box (because there is no entity like MonthDay in the library, everything includes the year), but you can still define it:

import kotlinx.datetime.format.*
import kotlinx.datetime.*

fun main() {
    val format = DateTimeComponents.Format {
        chars("--"); monthNumber(); char('-'); dayOfMonth()
        alternativeParsing({ char('t') }) { char('T') }
        time(LocalTime.Formats.ISO)
    }
    format.parse("--01-13T12:00").let {
        println("Month is ${it.month}")
        println("Day is ${it.dayOfMonth}")
        println("Time is ${it.toLocalTime()}")
    }
}

Prints

Month is JANUARY
Day is 13
Time is 12:00

Runnable: https://pl.kotl.in/_Lo55HPq8

[Raphael TEYSSANDIER]

Nice! Thank you, I knew this lib was very powerful !