Linq group with sum function and nested records

Question

There is a collection:

List<Tuple<string, string, int>> sales = new List<Tuple<string, string, int>> {
            Tuple.Create("Store 1", "Product 1", 1000),
            Tuple.Create("Store 2", "Product 2", 2000),
            Tuple.Create("Store 3", "Product 3", 1500),
            Tuple.Create("Store 3", "Product 3", 10000)};

I'd like to get the tree:

Store 1, Product 1, 1000
   Store 1, Product 1, 1000
Store 2, Product 2, 2000
   Store 2, Product 2, 2000
Store 3, Product 3, 11500
   Store 3, Product 3, 1500
   Store 3, Product 3, 10000

I use this linq query to build the tree:

var group = from sale in sales
        group sale by new { sale.Item1, sale.Item2 } into g
        select new { g.Key.Item1, g.Key.Item2, Sum = g.Sum(e => e.Item3),nestedsales = (from s in g select s) };

and this code for output:

foreach (var e in group)
{
    Console.WriteLine(e.Item1 + ", " + e.Item2 + ", " + e.Sum);
    foreach(var sale in e.nestedsales )
    {
        Console.WriteLine('\t' + sale.Item1 + ", " + sale.Item2 + ", " + sale.Item3);
    }
}

It works fine! I just wonder, is it optimal query? I mean, is it possible to build the tree without adding fourth field - nestedsales in the result of the query?

Answer 1

Yes , "nestedsales" is not necessary :

var group = sales.GroupBy(sale=>new { sale.Item1, sale.Item2 });
foreach (var e in group)
{
    Console.WriteLine(e.Key.Item1 + ", " + e.Key.Item2 + ", " + e.Sum(t=>t.Item3));
    foreach (var sale in e)
    {
        Console.WriteLine('\t' + sale.Item1 + ", " + sale.Item2 + ", " + sale.Item3);
     }
 }