Linq For Each - Need Advice

Question

I have this block of code.

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

Now I have a global list which I add each days appointments too eg Monday, Tuesday, Wed etc..

Then I run this:

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

Is there any whay I can run the Monday through Sunday appointments than having to write.

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);

Any ideas?

Answer 1

You can enumerate over values from DayOfWeek enum and get appointments of each day:

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);
}

If you need Monday to be first, then sort days:

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

BTW why you are adding appointments day by day? Looks like you can add all at once. If you want to add appointments in order starting from Monday:

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

Use Enum.GetValues to get all possible DayOfWeek values:

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

And AddRange to add more than one element to Appointments at once:

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

Or just create Appointments directly from your query:

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

Answer 3

Try this:

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);

Update : I didn't pay attension to ordering by days when monday should be first. To fix it replace

    .OrderBy(appointmentsOnDay => appointmentsOnDay.Day)

with

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