formatDateTime function

String formatDateTime(DateTime dateTime, { String? locale, String? pattern, DateFormatStyle? style, })

Formats a DateTime date and time according to locale conventions in pure Dart.

Combines localized date formatting with appropriate 12-hour (AM/PM) or 24-hour time formatting based on locale rules.

When locale is omitted, defaults to the active BloomI18n.instance.locale value.

final dt = DateTime(2026, 8, 23, 14, 30);
formatDateTime(dt, locale: 'en-US'); // "8/23/2026, 2:30 PM"
formatDateTime(dt, locale: 'fr-FR'); // "23/08/2026 14:30"

See also:

• formatDate, for date-only formatting.
• formatRelativeTime, for relative time formatting ("5 minutes ago").
• localizedDateTime, top-level convenience shorthand.

Implementation

String formatDateTime(
  DateTime dateTime, {
  String? locale,
  String? pattern,
  DateFormatStyle? style,
}) {
  if (pattern != null) {
    final loc = (locale ?? BloomI18n.instance.locale.value).replaceAll('_', '-');
    final lang = loc.split('-').first.toLowerCase();
    return _formatDateWithPattern(dateTime, pattern, lang);
  }

  final datePart = formatDate(dateTime, locale: locale, style: style);
  final loc = (locale ?? BloomI18n.instance.locale.value).replaceAll('_', '-');
  final lang = loc.split('-').first.toLowerCase();

  final h24 = dateTime.hour.toString().padLeft(2, '0');
  final min = dateTime.minute.toString().padLeft(2, '0');
  final h12 = (dateTime.hour == 0 ? 12 : (dateTime.hour > 12 ? dateTime.hour - 12 : dateTime.hour)).toString();
  final ampm = dateTime.hour < 12 ? 'AM' : 'PM';

  if (['en-us', 'en-ca'].contains(loc.toLowerCase())) {
    return '$datePart, $h12:$min $ampm';
  } else if (['fr', 'de', 'es', 'it', 'ru'].contains(lang)) {
    return '$datePart $h24:$min';
  }
  return '$datePart $h24:$min';
}