Question

I have a linq query that needs grouping on an id to count rows of 2 status values, then I would like to call a method that performs a calculation on the resulting counts. Perhaps someone can help me understand a better way to do this. When I run this I see an exception that the ‘calcRate’ is not recognized by linq, but I’ve done something similar before and it works fine. I may be approaching this incorrectly as well:

var query = from c in (context.table
    .Where(s => s.date >= startDate && s.date <= endDate)
    .GroupBy(s => new { s.id })
    .Select(s => new
        {
            id = h.Key.id,
            rate = calcRate(h.Count(s=>s.status == 1), h.Count(s=>s.status != 3))
        }).ToList())
        select new { id = c.id, rate = c.rate };

Answer 1

You should do the part that the DB can do in the DB and then use .AsEnumerable() to bring the results back into .NET to finish the calculations.

var query = context.table
    .Where(s => s.date >= startDate && s.date <= endDate)
    .GroupBy(s => s.id)
    .Select(s => new
        {
            id = s.Key,
            rateArg1 = s.Count(s=>s.status == 1),
            rateArg2 = s.Count(s=>s.status != 3)
        })
    .AsEnumerable()
    .Select(s => new { s.id, rate = calcRate(s.rateArg1, s.rateArg2)});