Question

I have a List of items with following structure:

1. Id
2. DateTime
3. Weight

How can group them by Id and Date of Date field (which is DateTime) and have the total weight of the group? I want something like this:

1. Id
2. Date
3. TotalWeight

Answer 1

If you want to group them with both ID and Date you can do it like this:

var grp = from x in items
          group by new {x.Id, x.DateTime.Date};

var result = grp.Select(x=>new {item = x.Key, TotalWeight = x.Sum(y=>y.Weight)});