Nested Group by LINQ

This is an easier way to accomplish nested groupings. I’ve tested it for in memory collections, whether or not your particular DB provider will handle it well might vary, or whether it performs well is unknown.

Assuming you had two properties, and wanted to group by both State and Country:

var grouped = People
  .GroupBy(l => new { l.State, l.Country})//group by two things
  .GroupBy(l=> l.Key.Country)//this will become the outer grouping


foreach(var country in grouped)
{
  foreach(var state in country)
  {
     foreach(var personInState in state)
     {
       string description = $"Name: {personInState.Name}, State: {state.StateCode}, Country: {country.CountryCode}";
       ...

     }
  }
}