Question

Hi Need some help with LINQ query.
I have entity called Shift. This entity has several value field but the ones I am intressted in are ShiftID (int), ShiftDate (DateTime) and GrossMount (decimal(10,2). And this needs to be grouped by month (binding this to a graph in ASP.NET).

I need data for the last 12 months grouped by month.
I have come a bit on the way with this post: Linq to Entity, selecting group without value but not quite all the way.
This is my code for now:

      public IQueryable<Shift> GetPastMonths(int months, string accountNumber)
    {
        _context = new EtaxiEnteties();
        var _date = DateTime.Today;
        var _firstOfMonth = new DateTime(_date.Year, _date.Month, 31);
        var _twelveMonthAgoFirstOfMonth = _firstOfMonth.AddMonths(-12);

        // Generate a collection of the months and years for the last 12 months
        var _monthYears = Enumerable.Range(-12, 12).Select(monthOffset => { var monthDate = _firstOfMonth.AddMonths(monthOffset); return new { y = monthDate.Year, m = monthDate.Month }; });

        var _data = (from _monthYear in _monthYears
                    join _i in
                         (from _i in _context.Shifts.Where(acc => acc.Account.AccountNumber == accountNumber)
                         where _i.ShiftDate >= _twelveMonthAgoFirstOfMonth && _i.ShiftDate < _firstOfMonth
                         group _i by new { y = _i.ShiftDate.Year, m = _i.ShiftDate.Month } into g
                         select new { ShiftID = g.Key, GrossAmount = g.Count() }) on _monthYear equals _i.ShiftID into j
                    from _k in j.DefaultIfEmpty()
                    select new Shift() { ShiftDate = new DateTime(_monthYear.y, _monthYear.m, 1), GrossAmount = _k != null ? _k.GrossAmount : 0 });

        return _data as IQueryable<Shift>;

    }

Now I have in return a collection of Shift objects, grouped by month but still missing the GrossAmount. Althoug i would need this from today date (only getting from 1 of current month).
Believe this is my main problem: GrossAmount = g.Count(), but I am not sure

Any LINQ specialist out there that could give me a push?

Answer 1

Use GrossAmount = g.Sum(x => x.GrossAmount) to calculate total GrossAmount value of grouped Shift entities. I believe you have typo in GrossAmount (GrossMount) property name.