Dart : parse date timezone gives UnimplementedError

Question

I need to parse a date in the following format in my Flutter application (come from JSON) :

2019-05-17T15:03:22.472+0000

According to the documentation, I have to use Z to get the time zone (last 5 characters in RFC 822 format), so I use the following :

new DateFormat("y-M-d'T'H:m:s.SZ").parseStrict(json['startDate']);

But it fails with error :

FormatException: Characters remaining after date parsing in 2019-05-17T15:03:22.472+0000

Here is another test :

/// THIS WORKS
try {
    print(new DateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS").format(DateTime.now()));
} catch (e) {
    print(e.toString());
}

/// THIS RETURNS `UnimplementedError` (as soon as I use a 'Z' or 'z') somewhere
try {
    print(new DateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ").format(DateTime.now()));
} catch (e) {
    print(e.toString());
}

Is Z implemented ?

Solution 1

From the DateFormat class docs:

DateFormat is for formatting and parsing dates in a locale-sensitive manner.

You're not asking to parse a locale-sensitive date string but rather an ISO 8601 date string, so thus you should not use the DateFormat class.

Instead, use the DateTime.parse method, which supports the format you described, per its docs:

Examples of accepted strings:

• ...
• "2002-02-27T14:00:00-0500": Same as "2002-02-27T19:00:00Z"

Solution 2

Sadly z and v patterns are not implemented.

Those won't be implemented until Dart DateTime's have time zone information

More info on this issue https://github.com/dart-lang/intl/issues/19