Can't random orderby while using LinqToExcel

Question

I am using the LinqToExcel project developed by MIT and hosted on Google Code at http://code.google.com/p/linqtoexcel/wiki/UsingLinqToExcel to parse my dataset from an excel table which looks something like this:

Part of the dataset

I'm trying to randomly pick 30 excel rows from my dataset containing area and length using the Linq OrderBy random number technique seen here:

public class Obj
{
    public double Area { get; set; }
    public double Length { get; set; }
}

namespace LinqToExcel.Screencast
{
    class Program
    {
        static void Main()
        {
            var excel = new ExcelQueryFactory();
            excel.FileName = @"C:\\radno\\jame.xls";

            Random rnd = new Random();

            var listExcel = from x in excel.Worksheet<Obj>()
                select x;

            var orderedList = listExcel.OrderBy(r => rnd.Next());

            foreach (var u in orderedList.Take(30))
            {
                Console.WriteLine($"the area is {u.Area} while length is {u.Length}");
            }
        }
    }
}

But it's not working because I always get the same first 30 pairs. Am I doing something wrong here? Should this work and is this a LinqToExcel bug?

I've tryed the list.OrderBy(x => Guid.NewGuid()) trick, but I get the same results.

Answer 1

It looks like OrderBy is able to work only when you point to exact column. I checked libary sources. If you go to : https://github.com/paulyoder/LinqToExcel/blob/master/src/LinqToExcel/Query/SqlGeneratorQueryModelVisitor.cs (line 113) You can see what is taken to OrderBy SQL. It ignores any method calls and saves only column name. It's not going to work in this approach. As a workaround you can do .ToList() before .OrderBy().