FormatException on specific date and time (very strange)

[akhatriST]

Describe the bug
Getting the following exception on this specific date range only i.e. 23-03-12 02:00:00 to 23-03-12 02:59:59 with the following message

FormatException: Error parsing 23-03-12 02:00:00, invalid hour value: 2 in en_US with time zone offset -4:00:00.000000. Expected value between 3 and 3. Date parsed as 0023-03-12 03:00:00.000..

To Reproduce
The timezone should be either UTC -4, -5, -6, -7 and running a local test as following will reproduce it. Please note that this works fine for all the time windows except 02:00:00 till 02:59:59

void main(List<String> arguments) {
    String date = "23-03-12 02:00:00";
    DateTime? dateTime = DateFormat('y-MM-dd HH:mm:ss').parseStrict(date).toLocal();
}

Expected
The library should work as expected on the above mentioned time range.

[mosuem]

This can be reproduced with

DateFormat('yy').parseStrict("23");

as the verify method checks if the year is valid, where 23 is not in the valid range of 2023 to 2023.

This should be fixed by adapting the validation code to check for the _hasAmbiguousCentury variable.

[akhatriST]

The issue I am facing is due to the Daylight saving adjustment in the mentioned timezones, which occurs on 12 March every year, hence the verify method fails because there is no consideration of Daylight saving.

[mosuem]

I am not sure I understand - the problem you described in the first post is reproducible without any specific reference to a time, just using the year. Could you elaborate?

[akhatriST]

The issue I am facing is specific to the time (particularly hour) and not the year. If you try to parse this date 23-03-12 02:00:00 with this format y-MM-dd HH:mm:ss then the time returned is DayLight saving adjusted, i.e. 23-03-12 03:00:00 which then goes through the series of verify checks as I am using the DateFormat.parseStrict method. It fails to verify the Hour field and throws the FormatException with the following Stack trace;

DateBuilder._verify (date_builder.dart:159)
DateBuilder.verify (date_builder.dart:131)
DateFormat._parse (date_format.dart:400)
DateFormat.parseStrict (date_format.dart:384)
Data.getDate (data.dart:875)

Hope the above stack trace helps.

[mosuem]

The format y-MM-dd HH:mm:ss would expect the date to be 2023-03-12 02:00:00, which then works. Does this solve your problem?

[alan-knight]

Try it on the 26th of March at 2:00am. This failure depends on the underlying OS/browser's daylight savings time transition code. This is different between North America/Europe/elsewhere. But also, it's not that there's no accommodation of daylight savings time. It's failing precisely because it does take it into account. There are DateTimes that are not valid because they don't exist. If you try to create one, the underlying DateTime code will adjust it to be something different. It fails validation rather than silently changing the value.

…

On Mon, Mar 27, 2023 at 8:58 AM Moritz ***@***.***> wrote: The format y-MM-dd HH:mm:ss would expect the date to be 2023-03-12 02:00:00, which then works. Does this solve your problem? — Reply to this email directly, view it on GitHub <#483>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AA2QU6DMFBTBCUICUZG7S53W6GFGDANCNFSM6AAAAAAWAYVR3U> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[slgobinath]

Facing the same error in Eastern Timezone. Any fix?

[mosuem]

The error is that this DateTime does not exist, so there is no fix for this. This issue is open for fixing #483 (comment).