Custom locales

Register a locale under any code to add a language or replace the strings of a built-in one. A registered locale is used for pattern, relative, calendar and duration formatting.

Extend a built-in locale

To change only a few strings, extend the built-in class and override what you need.

class MyVietnamese extends ViLocale {
  @override
  String ordinalNumber(int n) => 'ngày thứ $n';
}

SupportedLocalesUtils.registerLocale('vi', MyVietnamese());

Add a new locale

Extend DateFormatterLocale. Calendar and duration strings are optional; without them those APIs use English.

class MyLocale extends DateFormatterLocale {
  @override
  String code() => 'xx';

  @override
  String ordinal(int n) => '.';

  @override
  String ordinalNumber(int n) => '$n.';

  @override
  RelativeDateTime relativeDateTime() => MyRelativeTime();

  @override
  RelativeDateTime shortRelativeDateTime() => MyShortRelativeTime();

  @override
  CalendarDateTime calendarDateTime() => MyCalendar(); // optional

  @override
  DurationUnits durationUnits() => MyDurationUnits(); // optional
}

SupportedLocalesUtils.registerLocale('xx', MyLocale());

Interfaces

Interface	Strings
RelativeDateTime	prefixes, suffixes and units of relative times ("5 minutes ago")
DirectionalRelativeDateTime	optional: different unit forms for past and future (Czech, Slovak)
CalendarDateTime	today, tomorrow, yesterday, next/last weekday; receives isSameWeek
DurationUnits	standalone unit forms for humanized durations

Flutter users

The base class used to be called Locale, which clashed with Flutter's Locale. It is now DateFormatterLocale; the old name remains as a deprecated typedef.