Question

I am grouping a collection of tools using the following code:

 var filteredTools = from t in tools
                               group t by new { t.ModuleName,t.Number}
                               into g
                               select new { ModuleName = g.Key, Values = g };

tools is a simple collection defined as follows:

List<Tool> tools

After grouping is performed I get 3 rows back (from 40 rows) so grouping is working. The rows have a key of g.Key and Values are the grouping conditions. Is there anyway to relate it back to the original tools. Maybe the key should be unique to each tool so after the grouping is performed I can fetch the original tool from the tools collection.

Answer 1

Yes, the tools still exist within each group:

foreach (var group in filteredTools) 
{
    // This is actually an anonymous type...
    Console.WriteLine("Module name: {0}", group.ModuleName);
    foreach (Tool tool in group.Values)
    {
        Console.WriteLine("  Tool: {0}", tool);
    }
}

To be honest, you don’t really need your anonymous type here for the select. You could use:

var filteredTools = tools.GroupBy(t => new { t.ModuleName,t.Number});
foreach (var group in filteredTools) 
{
    // This is actually an anonymous type...
    Console.WriteLine("Module name: {0}", group.Key);
    foreach (Tool tool in group)
    {
        Console.WriteLine("  Tool: {0}", tool);
    }
}