type 'Future<DateTime>' is not a subtype of type 'DateTime'

Question

In my Flutter app I'm fetching some datetime info from an API but getting this error. I'm using Provider.

My display widget has this in didChangeDependencies:

_userDateTime = Provider.of<TimeZones>(context, listen: false).getDateTime(0);
print('didChangeDependencies()');
print(_localDateTime.toString());
print(DateFormat("E d MMM hh:mm a").format(_localDateTime));

and this outputs ok up until I try to use that datetime object.

flutter: didChangeDependencies()
flutter: Instance of 'Future<DateTime>'

======== Exception caught by widgets library 

So I know that TimeZones is returning a DateTime object, I can test the values and see that it's right.

How do I get my widget to accept the Future and treat it as a normal DateTime?

or is there a better approach?

Answer 1

It looks like your getDateTime(0) call returns a future. Try to await it:

_userDateTime = await Provider.of<TimeZones>(context, listen: false).getDateTime(0);

Answer 2

Add async to the didChangeDependencies function and await for the getDatetime result like this:

_userDateTime = await Provider.of<TimeZones>(context, listen: false).getDateTime(0);

Answer 3

In didChangeDependencies I changed the provider request to

Provider.of<TimeZones>(context, listen: false)
          .setDateTime(-1, 0)
          .then((_)

and in my builder I call

final tzData = Provider.of<TimeZones>(context);
    DateTime _localDateTime = tzData.getDateTime(-1);
    DateTime _userDateTime = tzData.getDateTime(0);

and it seems to work as expected. More testing needed.