LINQ - how to get next three business days excluding dates in table? - linq

Question

I need to find the next three available business days for a scheduling application. What is available depends upon excluded dates in a table. So...as long as the date is not in my table and not a Saturday or Sunday, I want the next three. I'd like to find an efficient way of doing this.
I need to return a List<DateTime>. The table is simple - ExcludedDates has an ID and a DateTime with the excluded date.
I'd like to have a single LINQ query expression but can't figure it out...thanks to all in advance and I apologize if this is trivial or obvious - it isn't to me.

Answer 1

Try this...
DateTime start = DateTime.Now.Date;
var result = Enumerable.Range(1, 10) // make this '10' higher if necessary (I assume you only exclude non-workingdays like Christmas and Easter)
.Select(offset => start.AddDays(offset))
.Where(date => !( date.DayOfWeek == DayOfWeek.Saturday || date.DayOfWeek== DayOfWeek.Sunday))
.Where(d=> !exceptionTable.Any(date => date == d))
.Take(3).ToList();

Answer 2

List<DateTime> result = (from i in Enumerable.Range(1, excludeTable.Rows.Count + 6)
let date = inputDate.AddDays(i)
where date.DayOfWeek != DayOfWeek.Saturday &&
date.DayOfWeek != DayOfWeek.Sunday &&
!excludeTable.Rows.Cast<DataRow>().Select(r => (DateTime) r["ExcludeDate"]).Contains(date)
select date).Take(3).ToList();
excludeTable.Rows.Count + 6 is to cover the worst case where you skip over every thing in the excludeTable and then you have to skip over another weekend.

Answer 3

This assumes that a month will be reasonable depending on your excluded dates.
DateTime date = DateTime.Today;
// first generate all dates in the month of 'date'
var dates = Enumerable.Range(1, DateTime.DaysInMonth(date.Year, date.Month)).Select(n => new DateTime(date.Year, date.Month, n));
// then filter the only the start of weeks
var results = (from d in dates
where d.DayOfWeek != DayOfWeek.Saturday && d.DayOfWeek != DayOfWeek.Saturday && !excludes.Any(i => i.DateTime.Date == d.Date) && date < d
select d).Take(3);

Answer 4

var excludedList = new List<long>() { DateTime.Parse("2011-07-27").Ticks };
var week = new List<long>(){
DateTime.Now.Date.Ticks,
DateTime.Now.Date.AddDays(1).Ticks,
DateTime.Now.Date.AddDays(2).Ticks,
DateTime.Now.Date.AddDays(3).Ticks,
DateTime.Now.Date.AddDays(4).Ticks,
DateTime.Now.Date.AddDays(5).Ticks,
DateTime.Now.Date.AddDays(6).Ticks,
DateTime.Now.Date.AddDays(7).Ticks,
DateTime.Now.Date.AddDays(8).Ticks
};
var available = (from d in week.Except(excludedList)
where new DateTime(d).DayOfWeek != DayOfWeek.Saturday && new DateTime(d).DayOfWeek != DayOfWeek.Sunday
select new DateTime(d)).Take(3);
foreach (var a in available)
Console.WriteLine(a.ToString());