Question

I have the following linq expression pulling all data from my database:

var items = response.Select(a => a.SessionLocationID).ToArray();
mdl = _meetingRepository.Select<SessionLocation>()
    .OrderBy(a => a.SessionDT).ThenBy(a => a.SessionEndTime);

Now I want to group by the field ActualRoom and only the ones with ActualRoom count > 3

Is that possible?

Answer 1

You can use GroupBy, just keep in mind that you are losing the ordering you already did so I would start off before you do the sorting:

var groups =  _meetingRepository.Select<SessionLocation>()
                                .GroupBy(x => x.ActualRoom)
                                .Where(g => g.Count() > 3)

To have sorted groups – assuming preserving the count as a separate property is not neccessary you can just project to an IEnumerable of IEnumerable<SessionLocation>:

var groups =  _meetingRepository.Select<SessionLocation>()
                                .GroupBy(x => x.ActualRoom)
                                .Where(g => g.Count() > 3)
                                .Select(g => g.OrderBy(x => x.SessionDT).ThenBy(x => x.SessionEndTime));