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How to specify a TimeZone when creating a DateTime object in Dart/Flutter?

Dart?flutter does not appear to allow a timezone (eg: "Australia/Sydney" or "America/Detroit") to be specified when creating a DateTime object. Either the local timezone will be used, or UT may be specified.

Is anyone aware of a workaround?

There's the Dart package TimeZone, but it appears to be unusable within a flutter app.

See https://pub.dartlang.org/packages/timezone for the package I'm referring to.

EDIT: The timezone package does work in Flutter, with some setup. See Richard Heap's answer below.

Solution

  • You have to do a bit of magic to get package:timezone to work in flutter.

    Extract whichever data file you need (there are 3: default, all and 2010-2020) and move it to your flutter assets folder. (I use 2018c_2010-2020.tzf, which is available in a branch.)

    Add it as an asset in pubspec.yaml:

      assets:
    - assets/2018c_2010-2020.tzf

    Then load that file on startup (e.g. from the initState of a top level StatefulWidget) and use it to initialise the database.

    ByteData tzf = await rootBundle.load('assets/2018c_2010-2020.tzf');
initializeDatabase(tzf.buffer.asUint8List());
...
Location newYork = getLocation('US/Eastern');

    I haven't tried, but you may even be able to load it from main if you mark it async.

    I also notice that I must have cloned the latest branch, as I see this in my pubspec

      timezone:
    path: ../../dart/source/timezone

    ... but looks like you just need to grab 0.5.0-dev-2 from pub

    dependencies:
  timezone: "^0.5.0-dev-2"