Support ? conditional in expressions

[matthewtsmith]

I have added some Date operators as MemberAccessors that are the following:

var dateStringFunctions = MemberAccessor<String>({
  'toDate': (i) => () {
        return parseDate(i);
      },
});

var dateNumFunctions = MemberAccessor<num>({
  'toDate': (i) => () {
        return DateTime.fromMillisecondsSinceEpoch(i.toInt());
      },
});

var dateFunctions = MemberAccessor<DateTime>({
  'format': (date) => (String format) {
        if (date == invalidDate) {
          return '';
        }
        if (format.isEmpty) {
          format = 'date_long';
        }
        var locale = PlatformDispatcher.instance.locale.languageCode;
        var dateFormat24 = PlatformDispatcher.instance.alwaysUse24HourFormat;
        DateFormat formatter;
        try {
          switch (format) {
            case 'date_short':
              formatter = DateFormat.yMd(locale);
              break;
            case 'date_long':
              formatter = DateFormat.yMMMd(locale);
              break;
            case 'date_time_short':
              formatter = DateFormat.yMd(locale);
              if (dateFormat24) {
                formatter = formatter.add_Hm();
              } else {
                formatter = formatter.addPattern("h:mm a");
              }
              break;
            case 'time':
              formatter = DateFormat.Hms(locale);
              break;
            default:
              formatter = DateFormat(format);
          }

          var str = formatter.format(date.toLocal());
          return str;
        } catch (e, s) {
          logError('Invalid date format', e, s);
          return "date format invalid";
        }
      }
});

I can then use an expression like the following:

record.myStringifiedDate.toDate().format('date_short')

However, when the myStringifiedDate field is null it throws an exception. I've attempted to use an expression like

record.myStringifiedDate?.toDate().format('date_short') ?? ''

When I try that I receive the error type 'Null' is not a subtype of type 'Function'

I'm wondering if this is possible and I'm just writing it incorrectly or if support for ? can be added. If you see a way for it to be added I'm happy to contribute if you can provide me some guidance on how to implement this feature.

I see that this can be worked around by using ${record.date != null ? record.date.toDate().format('date_short') : ''} but I'm looking for a more succinct way to write this since null values are common in our system. I can also envision having member functions that could return null such as toDate returning null because the date does not match a supported format.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.