How do I make a formatter for this `val pubDate = ...

# kotlinx-datetime

[dave08]

How do I make a formatter for this val pubDate = "Sun, 12 Sep 2021 15:35:34 +0300"? I'm posting my current attempt in the thread.

[dave08]

val pubDateFormat = DateTimeComponents.Format {
    dayOfWeek(DayOfWeekNames.ENGLISH_ABBREVIATED)
    chars(", ")
    dayOfMonth()
    char(' ')
    monthName(MonthNames.ENGLISH_ABBREVIATED)
    char(' ')
    year()
    char(' ')
    hour(); char(':'); minute(); char(':'); second()
    offsetHours()
//    offsetMinutesOfHour()
}

pubDateFormat.parse(pubDate).toLocalDateTime()

[dave08]

I don't see how to parse the +0300...

[Robert Jaros]

have you tried without char('+') ? I would assume it's already in the offset part.

[dave08]

yeah

[dave08]

I get a funny error (I fixed the above code), that it's finding a 2 instead of +

[Robert Jaros]

char(' ') after second() perhaps?

[dave08]

Caused by: kotlinx.datetime.internal.format.parser.ParseException: Errors: position 29: 'There is more input to consume', position 12: 'Expected - but got 2', position 12: 'Expected + but got 2'
at kotlinx.datetime.internal.format.parser.Parser.match-impl(Parser.kt:197)
at kotlinx.datetime.internal.format.parser.Parser.match-impl$default(Parser.kt:186)
at kotlinx.datetime.format.AbstractDateTimeFormat.parse(DateTimeFormat.kt:134)
... 37 more

[dave08]

val pubDateFormat = DateTimeComponents.Format {
    dayOfWeek(DayOfWeekNames.ENGLISH_ABBREVIATED)
    chars(", ")
    dayOfMonth()
    char(' ')
    monthName(MonthNames.ENGLISH_ABBREVIATED)
    char(' ')
    year()
    char(' ')
    hour(); char(':'); minute(); char(':'); second(); char(' ')
    offsetHours()
//    offsetMinutesOfHour()
}

[dave08]

https://pl.kotl.in/mWGWSAZAk

[Robert Jaros]

uncomment offsetMinutesOfHour()

[dave08]

👍🏼 Yeah, it ended up being that char(' ') before the offsets that messed my previous tests up, thanks!

[dave08]

And in Kotlin notebook it gave me that funny error, whereas in playground it told me that there's more input left to parse...

[dave08]

But what's funny is that it doesn't seem to consider that offset...?

[dave08]

2021-09-12T153534Z

[dave08]

pubDateFormat.parse(pubDate).toLocalDateTime().toInstant(TimeZone.UTC)

[Robert Jaros]

LocalDateTime doesn't have any offset.

[dave08]

So it just swallows it up?

[dave08]

Is there maybe a way to make an Instant out of that that does consider the time zone?

[Robert Jaros]

pubDateFormat.parse(pubDate).toInstantUsingOffset()

[Robert Jaros]

https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime.format/-date-time-components/to-instant-using-offset.html

[dave08]

👍🏼 I hadn't noticed that one (the IDE doesn't always put that on the top of the list...), thanks!

[Dmitry Khalanskiy [JB]]

Do you maybe just need this? https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime.format/-date-time-components/-formats/-r-f-c_1123.html

[dave08]

Now after all that, it seems like I need to output this to a postgres date field with the YYYY-MM-DD format... what's the easiest way to do that from here?

[dave08]

It seems like format() on LocalDate doesn't take in a DateTimeComponents.Format....

[dave08]

Ok, I think I figured this out finally:

val postgresDateFormat = LocalDate.Format {
        year(); char('-'); monthNumber(); char('-'); dayOfMonth()
    }

DateTimeComponents.Formats.RFC_1123.parse(pubDate!!)
        .toLocalDate().format(postgresDateFormat)

[Dmitry Khalanskiy [JB]]

That's https://kotlinlang.org/api/kotlinx-datetime/kotlinx-datetime/kotlinx.datetime/-local-date/-formats/-i-s-o.html, or just date.toString()