flutter - 无法应用正确的逻辑来获取约会日期

Question

我一直在开发一个约会应用程序，约会时段从当前时间到接下来的 2 天的早上 7 点到晚上 8 点开始。除非有人预订，否则每半小时可预约一次。因此，如果用户想预约今天的约会，它将禁用已经过去的时间并在当前时间 1 小时后显示可用时段。现在，我陷入困境的地方是我创建了一个函数，该函数列出了当前时间之后的所有可用约会，但不知道如何获取值来 flutter 小部件。我每次都为空

 class GetAppointment with ChangeNotifier {
    final String appId, allotedCrew, allotedSlot, usedSlot, totalTimeSlots;
    final DateTime totalDurationinHr;
    dynamic availableTimeSlotsFm, currentDate;
    bool slotAvailable, dayAvailable;
    
    GetAppointment({
       this.appId,
       this.allotedCrew,
       this.allotedSlot,
       this.usedSlot,
       this.totalTimeSlots,
       this.totalDurationinHr,
       this.availableTimeSlotsFm,
       this.currentDate,
       this.slotAvailable: true,
       this.dayAvailable: true});
    }

    extension on DateTime {
        DateTime roundDown({Duration delta = const Duration(minutes: 30)}) {
        return DateTime.fromMillisecondsSinceEpoch(this.millisecondsSinceEpoch -
        this.millisecondsSinceEpoch % delta.inMilliseconds);
    }
}

class Appointments with ChangeNotifier {
    Map<String, GetAppointment> _appointmentList = {};

    Map<String, GetAppointment> get items {
        return {..._appointmentList};
    }
    
    generateBookingSlots() {
        final endTime = DateTime(now.year, now.month, now.day, 23, 60, now.second);
        final startTime = DateTime(now.year, now.month, now.day, 6, 60, now.second);
        var currentTime = DateTime.now();
        var availableTimeSlots = DateTime.now();
        var currentDate, availableTimeSlotsFm;
        final diff_dy = endTime.difference(startTime).inDays;
        final diff_hr = endTime.difference(startTime).inHours;
    
        //List available day from current day
        for (int i = 0; i <= 3; i++) {
            int a = 0;
            if ((diff_hr * 2) <= 0) {
               a = 1;
            }
            currentDate = DateTime.now().add(Duration(days: 1) * (i + a));
        } 
        
        // List numbers of hours in single day
        final listAllTime = List.generate(diff_hr * 2, (index) {
        final totalDuration = startTime.add(Duration(minutes: 30));
        final totalTimeSlots =
             DateFormat.jm().format(startTime.add(Duration(minutes: 30) * index));

        if (currentTime.difference(startTime).inHours > 0 &&
             currentTime.isBefore(endTime) &&
             availableTimeSlots.isBefore(endTime)) {
             availableTimeSlots = currentTime.add(Duration(minutes: 30) * index);
             availableTimeSlots.roundDown(delta: Duration(minutes: 30));
             availableTimeSlotsFm = DateFormat.jm()
                .format(availableTimeSlots.roundDown(delta: Duration(minutes: 30)));
             // availableTimeSlots.roundDown();
         }
         _appointmentList.putIfAbsent(
             index.toString(),
            () => GetAppointment(
                appId: index.toString(),
                allotedCrew: "2",
                allotedSlot: "2",
                usedSlot: "2",
                totalTimeSlots: totalTimeSlots,
                totalDurationinHr: totalDuration,
                availableTimeSlotsFm: availableTimeSlotsFm,
                currentDate: currentDate,
             ));
        return {
           'totalDurationinHr': totalDuration,
           'totalTimeSlotsFm': totalTimeSlots,
           'availableTimeSlotsFm': availableTimeSlotsFm,
           'currentDate': currentDate
        };
      });
     // notifyListeners();
  }

它应该是这样的，我可以处理 UI 部分，只是不知道如何以简单的列表格式获取这些时间

Answer 1

而不是尝试这样做

List<Map<String, dynamic>> get generateBookingSlots {
    final endTime = DateTime(now.year, now.month, now.day, 23, 60, now.second);
    final startTime = DateTime(now.year, now.month, now.day, 6, 60, now.second);
    var currentTime = DateTime.now();
    var availableTimeSlots = DateTime.now();
    var currentDate, availableTimeSlotsFm;
    final diff_dy = endTime.difference(startTime).inDays;
    final diff_hr = endTime.difference(startTime).inHours;

    //List available day from current day
    for (int i = 0; i <= 3; i++) {
        int a = 0;
        if ((diff_hr * 2) <= 0) {
           a = 1;
        }
        currentDate = DateTime.now().add(Duration(days: 1) * (i + a));
    } 
    
    // List numbers of hours in single day
    final listAllTime = List.generate(diff_hr * 2, (index) {
    final totalDuration = startTime.add(Duration(minutes: 30));
    final totalTimeSlots =
         DateFormat.jm().format(startTime.add(Duration(minutes: 30) * index));

    if (currentTime.difference(startTime).inHours > 0 &&
         currentTime.isBefore(endTime) &&
         availableTimeSlots.isBefore(endTime)) {
         availableTimeSlots = currentTime.add(Duration(minutes: 30) * index);
         availableTimeSlots.roundDown(delta: Duration(minutes: 30));
         availableTimeSlotsFm = DateFormat.jm()
            .format(availableTimeSlots.roundDown(delta: Duration(minutes: 30)));
         // availableTimeSlots.roundDown();
     }

     return {
       'totalDurationinHr': totalDuration,
       'totalTimeSlotsFm': totalTimeSlots,
       'availableTimeSlotsFm': availableTimeSlotsFm,
       'currentDate': currentDate
     }
   });
   return listAlltime.toList();
}

现在您可以通过调用 generateBookingSlots 轻松获取您的数据如果您需要获取个人数据，请执行此操作

List<Map<String, dynamic>> get totalDurationinHr{
    final totalDurationinHr = List.generate(generateBookingSlots.length, (index) {
          return {'totalDurationinHr' :generateBookingSlots[index]['totalDurationinHr'] }
    }

}