custom map example

delta.custom.map.statistics

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Web.Mvc;
using Delta.Common.Reflection;

namespace CustomMap
{
    public class ServiceDataStatistic 
    {
        public DateTime? Date { get; set; }
        public long? In { get; set; }
        public long? Out { get; set; }
    }

    public class GeneralStatistic
    {
        public DateTime? Date { get; set; }
        public long? Bytes { get; set; }
    }

    public static class DataGen
    {
        public static IEnumerable<ServiceDataStatistic> GetStatisticsFromServer()
        {
            yield return new ServiceDataStatistic
                {
                    Date = DateTime.Now.AddMonths(-1),
                    In = 100,
                    Out = 200,
                };

            yield return new ServiceDataStatistic
            {
                Date = DateTime.Now.AddMonths(-2),
                In = 50,
                Out = 100,
            };
        }
    }

    public static class Extensions
    {
        public static IEnumerable<GeneralStatistic> GetGeneralStatistic(
            this IEnumerable<ServiceDataStatistic> statistics, Expression<Func<ServiceDataStatistic, long?>> expression)
        {
            var nameForExpression = ExpressionHelper.GetExpressionText(expression);
            
            return statistics.Select(s => new GeneralStatistic
                                            {
                                                Date = s.Date,
                                                Bytes = s.GetPropValue<long>(nameForExpression)
                                            });            
        }
    }

    class Program
    {      
        static void Main(string[] args)
        {
            var a = DataGen.GetStatisticsFromServer().GetGeneralStatistic(s1 => s1.In);

            var b = DataGen.GetStatisticsFromServer().GetGeneralStatistic(s2 => s2.Out);
        }
    }
}

@ Mathias: Deze code gaat er vanuit dat de expression dus een property bevat, anders gaat het verder fout bij s.GetPropValue. Dit kan je evt zelf safer maken. Een goede achtergrond is mijn artikel: http://www.martijnburgers.net/post/2011/06/05/The-basics-behind-static-reflection.aspx