如何从Cloud Firestore获取数据以显示在事件日历中

Question

如何从Cloud Firestore获取数据以显示在事件日历中

_selectedDay = DateTime.now();
var eventA = _buildBody(context);

_events = {    
  DateTime(2019, 5, 23): [eventA],
  DateTime(2019, 5, 24): ['Event B', 'Event C'],
  DateTime(2019, 5, 1): ['Event A', 'Event B', 'Event C', 'Event D', 'Event E', 'Event F', 'Event G'],
  DateTime(2019, 5, 29): Set.from(['Event A', 'Event A', 'Event B']).toList(),
  DateTime(2019, 5, 30): ['Event A', 'Event A', 'Event B'],     
};