how to get unique list in csharp

Code Example - how to get unique list in csharp

                
                        using(var dataModel = new DataModel())
{
  var classes = dataModel.Attributes.Where(a => a.Field == "Class").Select(a => a.Key).Distinct().ToList();
}
                    
                
 

csharp get distinct values all fields from list

                        
                                if (!IsPostBack) {  
       GridView1.DataSource = GetProducts()
                              .GroupBy(o => new { o.Make, o.Model })
                              .Select(o => o.FirstOrDefault());
       GridView1.DataBind();
}