WCF Operation Contract - Best way to get the result sorted by any column

Question

I am trying to find the best way to implement a service method that can get the data and also the consumer must have option to specify the coumnname in which the result has to be sorted.

[OperationContract]
void GetAllMoviesSorted();

public List<MovieData> GetAllMoviesSorted()
{
    return db.GetAllData(); 
}

The option I thought was to pass a column name enum as a parameter to the function and build a dynamic query. Is this the best way to implement this?

Regards, Jebli.

The requirement is to do it on the service side.I am sure that there should be some better option. The simplest think that i can do is to write LINQ query for sorting based on the column name. — Rad, Jun 15 '14 at 13:55

score 0 · Answer 1 · answered Jun 15 '14 at 15:30

If the columns to sort by are MovieData Class Properties:

public List<MovieData> getAllMoviesSorted(string column)
{
    List<MovieData> movieData = db.GetAllData();
    switch(column.ToUpper())
    {
        case "ORDERDATE":
            movieData = movieData.OrderBy(o=>o.OrderDate).ToList(); 
            break;
        // add more cases
        default:
            throw new Exception("Column " + column + " cannot be found.");       
    }
    return movieData;
}

score 0 · Answer 2 · answered Jun 15 '14 at 15:38

Thought I'd do a generic reflective version of @Lucas 's answer.

public List<MovieData> getAllMoviesSorted(string column)
{
    List<MovieData> movieData = db.GetAllData();
    var parameter = Expression.Parameter(typeof(MovieData));
    var lambda = Expression.Lambda(
                    Expression.PropertyOrField(parameter, column),
                    parameter);
    return movieData
            .AsQueryable()
            .OrderBy(lambda)
            .ToList();
}

Thanks Aron. This is what I was expecting. – Rad Apr 10 '15 at 05:48 — Rad, Apr 10 '15 at 05:48

score 0 · Accepted Answer · answered Apr 10 '15 at 07:37

I have found a much simpler way without using expression trees

 PropertyInfo pi = typeof(MovieData).GetProperty(orderbycolumn);
 values.OrderBy(x => pi.GetValue(x, null));

Please find the below sample code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace sfPerformance
{
    class MoviesDynamicOrderBy
    {
        static void Main(string[] args)
        {
            IQueryable<MovieData> MovieNameList = new List<MovieData>() { 
            new MovieData {Name = "Star Wars" , Rating = 7, Language = "Hollywood"},
            new MovieData {Name = "The Godfather" , Rating = 7, Language = "Hollywood"},
            new MovieData {Name = "The Lord Of The Rings" , Rating = 8, Language = "Hollywood"},
            new MovieData {Name = "Titanic" , Rating = 10, Language = "Hollywood"},
            new MovieData {Name = "Gone With The Wind" , Rating = 9, Language = "Hollywood"}            
            }.AsQueryable();

            //Ascending default
            MoviesDynamicOrderBy obj = new MoviesDynamicOrderBy();
            var result = obj.StudentOrderByColumn<MovieData>("Name", MovieNameList);

            foreach (var item in result)
            {
                Console.WriteLine(item.Name);
            }

            Console.WriteLine(Environment.NewLine);

            //Descending  
            var descendingResult = obj.StudentOrderByColumn<MovieData>("Name", MovieNameList, true);

            foreach (var item in descendingResult)
            {
                Console.WriteLine(item.Name);
            } 

            if (System.Diagnostics.Debugger.IsAttached)
                Console.Read(); 
        }

        public IOrderedQueryable<MovieData> StudentOrderByColumn<T>(string orderbycolumn, IQueryable<MovieData> values, bool isDescending = false) 
        { 
            PropertyInfo pi = typeof(MovieData).GetProperty(orderbycolumn);
            IOrderedQueryable<MovieData> sortedMovies;
            if(isDescending)
             sortedMovies = values.OrderByDescending(x => pi.GetValue(x, null)); 
            else 
             sortedMovies = values.OrderBy(x => pi.GetValue(x, null));

            return sortedMovies;
        }
    }

    public class MovieData
    {
        public string Name { get; set; }
        public int Rating { get; set; }
        public string Language { get; set; }
    }
}

WCF Operation Contract - Best way to get the result sorted by any column

3 Answers3