Question

Here’s my 2 classes

public class Item
{
    public string Path { get; set; }
    public List<Sub> Subs { get; set; }
}

public class Sub
{
    public string Name { get; set; }
}

private void Test()
{
    Sub sub1 = new Sub() { Name = "SUB1" };
    Sub sub2 = new Sub() { Name = "SUB2" };
    Sub sub3 = new Sub() { Name = "SUB3" };

    Item item1 = new Item() { Path = "/Path1" };
    Item item2 = new Item() { Path = "/Path2" };
    Item item3 = new Item() { Path = "/Path3" };

    item1.Subs.Add(sub1);
    item1.Subs.Add(sub2);

    item2.Subs.Add(sub1);
    item2.Subs.Add(sub3);

    item3.Subs.Add(sub1);
    item3.Subs.Add(sub2);
    item3.Subs.Add(sub3);

    List<Item> items = new List<Item>();
    items.Add(item1);
    items.Add(item2);
    items.Add(item3);
}

I want a grouped collection that looks something like this

sub1 -> item1, item2, item3

sub2 -> item1, item3

sub3 -> item2, item3

How can I accomplish this?

Thanks much!

Answer 1

I’m assuming item1, item2, item3 are part of a new List<Item> whose name is items

//List<Item> items = new List<Item>();
//items.Add(item1);
//items.Add(item2);
//items.Add(item3);

var groupedBySub = from item in items
                   from s in item.Subs
                   group item by s into g
                   select new{ Sug = g.Key, Items = g };