using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Linq.Expressions;

using System.Text;

​

​

public class Phone

{

    public double Price { get; set; }

    public string Brand { get; set; }

}

​

public class Db

{

    public static IQueryable<Phone> Phones

    {

        get

        {

            return new List<Phone>()

            {

                new Phone(){ Price = 2, Brand = "A"},

                new Phone(){ Price = 1, Brand = "B"}

            }.AsQueryable();

        }

    }

}

​

​

public static class Utility

{

    //makes expression for specific prop

    public static Expression<Func<TSource, object>> GetExpression<TSource>(string propertyName)

    {

        var param = Expression.Parameter(typeof(TSource), "x");

        Expression conversion = Expression.Convert(Expression.Property(param, propertyName), typeof(object));   //important to use the Expression.Convert 

        return Expression.Lambda<Func<TSource, object>>(conversion, param);

    }

​

    //makes deleget for specific prop

    public static Func<TSource, object> GetFunc<TSource>(string propertyName)

    {

        return GetExpression<TSource>(propertyName).Compile();  //only need to compiled expression

    }

​

    //OrderBy overload

    public static IOrderedEnumerable<TSource> OrderBy<TSource>(this IEnumerable<TSource> source, string propertyName)

    {

        return source.OrderBy(GetFunc<TSource>(propertyName));

    }

​

    //OrderBy overload

    public static IOrderedQueryable<TSource> OrderBy<TSource>(this IQueryable<TSource> source, string propertyName) 

    {

        return source.OrderBy(GetExpression<TSource>(propertyName));

    }

}

​

​

public class Program

{

    public static void Dump(IEnumerable<Phone> phones, string mesg)

    {

        Console.WriteLine("\n" + mesg);

        foreach (var item in phones)

        {

            Console.WriteLine(String.Format("Brand = {0}, Price = {1}", item.Brand, item.Price));

        }

    }

​

    public static void Main(string[] args)

    {

​

        List<Phone> orderedByPrice = null;

        List<Phone> orderedByBrand = null;

​

        /*When using lambda expression*/

        orderedByPrice = Db.Phones.OrderBy(x => x.Price).ToList();

        orderedByBrand = Db.Phones.OrderBy(x => x.Brand).ToList();

        Dump(orderedByPrice, "lambda expression, Order By: Price");

        Dump(orderedByBrand, "lambda expression, Order By: Brand");

​

​

        /*When source is IQueryable*/

        orderedByPrice = Db.Phones.OrderBy("Price").ToList();

        orderedByBrand = Db.Phones.OrderBy("Brand").ToList();

        Dump(orderedByPrice, "Source is IQueryable, Order By: Price");

        Dump(orderedByBrand, "source is IQueryable, Order By: Brand");

​

        /*When source is IEnumerable*/

        orderedByPrice = Db.Phones.AsEnumerable().OrderBy("Price").ToList();

        orderedByBrand = Db.Phones.AsEnumerable().OrderBy("Brand").ToList();

        Dump(orderedByPrice, "Source is IEnumerable, Order By: Price");

        Dump(orderedByBrand, "Source is IEnumerable, Order By: Brand");

​

    }

}

​

​