Get a property of a collection (e.g. Id property of MyClass) as a string CSV

GetPropertyAsCSV.cs

  class MyClass
  {
      public int Id { get; set; } 
      public string FirstName { get; set; } 
      public string LastName { get; set; }           
        //...
  }

  public static string GetPropertyIdAsList()
  {
        const string seperator = ", ";      
      var list = new List<MyClass>();
        // ...
        return String.Join(seperator, list.Select(i => i.Id).ToList()); ;
  }