每个Linq-需要咨询

Question

我有这段代码。

var foundAppointments = ServiceLink.FindAppointments(User, SiteSecureKey);    
var MondayAppointments = foundAppointments.SelectMany(x => x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Monday)).ToList();

现在，我有了一个全局列表，我也添加了每天的约会，例如星期一，星期二，星期三等。

然后我运行：

Appointments.Add(MondayAppointments); ..........

除了周一至周日的约会，我还有什么需要写的。

var TuesdayAppointments = foundAppointments.SelectMany(x=>x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Tuesday)).ToList();
var WednesdayAppointments = foundAppointments.SelectMany(x=>x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Wednesday)).ToList();
var ThursdayAppointments = foundAppointments.SelectMany(x=>x.Where(y =>y.StartTime.Date.DayOfWeek == DayOfWeek.Thursday)).ToList();
var FridayAppointments = foundAppointments.SelectMany(x=>x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Friday)).ToList();
var SaturdayAppointments = foundAppointments.SelectMany(x => x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Saturday)).ToList();
var SundayAppointments = foundAppointments.SelectMany(x => x.Where(y => y.StartTime.Date.DayOfWeek == DayOfWeek.Saturday)).ToList();
Appointments.Add(TuesdayAppointments);
Appointments.Add(WednesdayAppointments);
Appointments.Add(ThursdayAppointments);
Appointments.Add(FridayAppointments);
Appointments.Add(SaturdayAppointments);
Appointments.Add(SundayAppointments);

有任何想法吗？

Answer 1

您可以从DayOfWeek枚举中枚举值，并获取每一天的约会：

var days = Enum.GetValues(typeof(DayOfWeek));
foreach (DayOfWeek dayOfWeek in days)
{
    var dayAppointments = foundAppointments.SelectMany(x => x.Where(y => y.StartTime.Date.DayOfWeek == dayOfWeek)).ToList();
    Appointments.Add(dayAppointments);
}

如果您需要星期一作为第一天，则对日期进行排序：

var days = Enum.GetValues(typeof(DayOfWeek)).Cast<DayOfWeek>()
               .OrderBy(d => d == DayOfWeek.Sunday)
               .ThenBy(d => d);

顺便说一句，为什么您每天都在增加约会？ 看起来您可以一次添加所有内容。 如果要从星期一开始按顺序添加约会：

var appintmentsToAdd = foundAppointments
     .SelectMany(x => x)
     .OrderBy(a => a.StartTime.Date.DayOfWeek == DayOfWeek.Sunday)
     .ThenBy(a => a.StartTime.Date.DayOfWeek)
     .ToList();

Appointments.Add(appintmentsToAdd);

Answer 2

使用Enum.GetValues获取所有可能的DayOfWeek值：

var days = Enum.GetValues(typeof(DayOfWeek)).Cast<DayOfWeek>().ToArray();

然后使用AddRange一次向Appointments中添加多个元素：

var foundAppointments = ServiceLink.FindAppointments(User, SiteSecureKey);    
Appointments.AddRange(days.Select(d => foundAppointments.SelectMany(x=>x.Where(y => y.StartTime.Date.DayOfWeek == d)).ToList());

或者直接从查询中创建Appointments ：

var Appointments.AddRange(days.Select(d => foundAppointments.SelectMany(x=>x.Where(y => y.StartTime.Date.DayOfWeek == d)).ToList()).ToList();

Answer 3

尝试这个：

IEnumerable<DayOfWeek> daysOfWeek = Enum.GetValues(typeof(DayOfWeek)).Cast<DayOfWeek>();

var appointmentsOnDaysOfWeek = daysOfWeek
    .GroupJoin(
        foundAppointments,
        dayOfWeek => dayOfWeek,
        appointment => appointment.StartDate.DayOfWeek,
        (day, appointments) => new
        {
            Day = day,
            Appointments = appointments.ToList()
        })
    .OrderBy(appointmentsOnDay => appointmentsOnDay.Day)
    .Select(appointmentsOnDay => appointmentsOnDay.Appointments);

Appointments.AddRange(appointmentsOnDaysOfWeek);

更新 ：我没有在周一应该是星期一的几天前开始订购。 要修复它，请更换

    .OrderBy(appointmentsOnDay => appointmentsOnDay.Day)

同

    .OrderBy(appointmentsOnDay => appointmentsOnDay.Day == DayOfWeek.Sunday)
    .ThenBy(appointmentsOnDay => appointmentsOnDay.Day)