Grouping a generic list via LINQ in VB.NET

Question

I need to take a collection and group it via Linq but all the examples I\'ve seen fail in some manner or other with some syntax difference that I can\'t quite lick.

My c

Answer 1

Here is the linq code I would write (in c# - sorry I couldn't complete it in VB)

var res = a.GroupBy(i=>i.EmailAddress )
    .Select(g=> new KeyValuePair(
                    g.Key, 
                    string.Join(",", g.Select(x=> x.AlertType ).ToArray()) 
            ));

This will give you the output you want in a collection of KeyValuePair

in order to group them by both LoadNumber and EmailAddress this would be the c# code:

var res = alerts
    .GroupBy(a => new { L = a.LoanNumber, E = a.EmailAddress })
    .Select(a => new
        {
            LoadNumber = a.Key.L,
            EmailAddress = a.Key.E,
            Types = string.Join(", ", a.Select(x => x.AlertType).ToArray())
        }).ToList();

where result is a List of a Complext type {LoadNumber, EmailAddress, Types}