Using Linq to group a list of objects into a new grouped list of list of objects
Your group statement will group by group ID. For example, if you then write:
foreach (var group in groupedCustomerList)
{
Console.WriteLine("Group {0}", group.Key);
foreach (var user in group)
{
Console.WriteLine(" {0}", user.UserName);
}
}
that should work fine. Each group has a key, but also contains an IGrouping<TKey, TElement>
which is a collection that allows you to iterate over the members of the group. As Lee mentions, you can convert each group to a list if you really want to, but if you're just going to iterate over them as per the code above, there's no real benefit in doing so.
var groupedCustomerList = userList
.GroupBy(u => u.GroupID)
.Select(grp => grp.ToList())
.ToList();