// @nuget: Z.EntityFramework.Classic

​

using System.Linq;

using System.Data.Entity;

using System.Linq.Expressions;

​

/*

 Example to provide dynamic sort by column name as string

 For a real application we would have code setup to alias column names to prevent a misspelled column name

*/

public class Program

{

    public static void Main()

    {

        using (var context = new EntityContext())

        {

            var list = context.Customers.OrderByColumn("City").ToList();

            FiddleHelper.WriteTable("Customers", list);

            list = context.Customers.OrderByColumnDescending("CustomerName").ToList();

            FiddleHelper.WriteTable("Customers", list);

            list = context.Customers.OrderByColumn("Country").ToList();

            FiddleHelper.WriteTable("Customers", list);

        }

​

    }

​

    public class EntityContext : DbContext

    {

        public EntityContext() : base(FiddleHelper.GetConnectionStringSqlServerW3Schools())

        {

​

        }

        public DbSet<Customer> Customers { get; set; }

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string CustomerName { get; set; }

        public string City{ get; set; }

        public string Country {get;set;}

    }

}

/*

 columnPath accepts navigations e.g. ContactTypeNavigation.ContactTitle in this case taken from NorthWind database

*/

public static class QueryableExtensions

{

    public static IOrderedQueryable<T> OrderByColumn<T>(this IQueryable<T> source, string columnPath) 

        => source.OrderByColumnUsing(columnPath, "OrderBy");

​

    public static IOrderedQueryable<T> OrderByColumnDescending<T>(this IQueryable<T> source, string columnPath) 

        => source.OrderByColumnUsing(columnPath, "OrderByDescending");

​

    public static IOrderedQueryable<T> ThenByColumn<T>(this IOrderedQueryable<T> source, string columnPath) 

        => source.OrderByColumnUsing(columnPath, "ThenBy");

​

    public static IOrderedQueryable<T> ThenByColumnDescending<T>(this IOrderedQueryable<T> source, string columnPath) 

        => source.OrderByColumnUsing(columnPath, "ThenByDescending");

​

    private static IOrderedQueryable<T> OrderByColumnUsing<T>(this IQueryable<T> source, string columnPath, string method)

    {

        var parameter = Expression.Parameter(typeof(T), "item");

        var member = columnPath.Split('.')

            .Aggregate((Expression)parameter, Expression.PropertyOrField);

        var keySelector = Expression.Lambda(member, parameter);

        var methodCall = Expression.Call(typeof(Queryable), method, new[] 

                { parameter.Type, member.Type },

            source.Expression, Expression.Quote(keySelector));

​

        return (IOrderedQueryable<T>)source.Provider.CreateQuery(methodCall);

    }

}