在 flutter 日期范围选择器中将两个日期之间的所有日期作为列表返回

Question

我从 flutter date_range_picker 只有两个日期，但我想要两个选定日期之间的日期列表。 感谢您的回答

Answer 1

尝试以下操作：

List<DateTime> getDaysInBeteween(DateTime startDate, DateTime endDate) {
    List<DateTime> days = [];
    for (int i = 0; i <= endDate.difference(startDate).inDays; i++) {
      days.add(startDate.add(Duration(days: i)));
    }
    return days;
  }

Answer 2

已接受的解决方案存在问题。 该代码大部分时间都可以正常运行，但会失败，因为它不考虑夏令时 (DST) / 夏令时 / 夏令时( https://en.wikipedia.org/wiki/Daylight_saving_time )。

结果，例如它将生成以下序列（注意间隙）：

2020-10-24 00:00:00.000
2020-10-25 00:00:00.000
2020-10-25 23:00:00.000 # Mind the Gap :)
2020-10-26 23:00:00.000

我认为，这是一种效果更好的替代解决方案。

List<DateTime> getDaysInBeteween(DateTime startDate, DateTime endDate) {
    List<DateTime> days = [];
    for (int i = 0; i <= endDate.difference(startDate).inDays; i++) {
      days.add(
        DateTime(
          startDate.year, 
          startDate.month, 
          // In Dart you can set more than. 30 days, DateTime will do the trick
          startDate.day + i)
      );
    }
    return days;
}

Answer 3

我总是这样：

final today = DateTime.now();
final monthAgo = DateTime(today.year, today.month - 1, today.day);

final List<DateTime> days = [];
for (int i = 0; i <= today.difference(monthAgo).inDays; i++) {
  days.add(monthAgo.add(Duration(days: i)));
}

Answer 4

在处理加法或减法等日期时，始终使用 UTC来避免 DST 等问题，然后将它们转换回本地时间。

此外，如果开始日期和结束日期不在同一月份，手动添加天数（如day + 1 ）可能会导致问题。

所以为了避免所有这样做： -

案例 1 - 获取包括开始和结束日期之间的天数：-

List<DateTime> getDaysInBetweenIncludingStartEndDate(
    {required DateTime startDateTime, required DateTime endDateTime}) {

  // Converting dates provided to UTC
  // So that all things like DST don't affect subtraction and addition on dates
  DateTime startDateInUTC =
      DateTime.utc(startDateTime.year, startDateTime.month, startDateTime.day);
  DateTime endDateInUTC =
      DateTime.utc(endDateTime.year, endDateTime.month, endDateTime.day);

  // Created a list to hold all dates
  List<DateTime> daysInLocalFormat = [];
  
  // Starting a loop with the initial value as the Start Date
  // With an increment of 1 day on each loop
  // With condition current value of loop is smaller than or same as end date
  for (DateTime i = startDateInUTC;
      i.isBefore(endDateInUTC) || i.isAtSameMomentAs(endDateInUTC);
      i = i.add(const Duration(days: 1))) {
    
    // Converting back UTC date to Local date before inserting in list
    // You can keep in UTC format depending on your case
    daysInLocalFormat.add(DateTime(i.year, i.month, i.day));
    
  }
  return daysInLocalFormat;
}

案例 2 - 获取不包括开始和结束日期之间的天数：-

List<DateTime> getDaysInBetweenExcludingStartEndDate(
    {required DateTime startDateTime, required DateTime endDateTime}) {

  // Converting dates provided to UTC
  // So that all things like DST don't affect subtraction and addition on dates
  DateTime startDateInUTC =
      DateTime.utc(startDateTime.year, startDateTime.month, startDateTime.day);
  DateTime endDateInUTC =
      DateTime.utc(endDateTime.year, endDateTime.month, endDateTime.day);

  // Created a list to hold all dates
  List<DateTime> daysInLocalFormat = [];
  
  // Starting a loop with the initial value as the next day of the Start Date
  // With an increment of 1 day on each loop
  // With condition current value of loop is smaller than end date
  for (DateTime i = startDateInUTC.add(const Duration(days: 1));
      i.isBefore(endDateInUTC);
      i = i.add(const Duration(days: 1))) {

    // Converting back UTC date to Local date before inserting in list
    // You can keep in UTC format depending on your case
    daysInLocalFormat.add(DateTime(i.year, i.month, i.day));
  }

  return daysInLocalFormat;
}