Question

Trying to order logs by logtype or by logType and thenBy DateTime but does not work.What am I missing?

      public enum LogType
    {
        Fatal,
        Error,
        Warn,
        Info,
        Debug,
        None,
    }
    public class Log
    {
        public DateTime LoggedDateTime { get; set; }
        public string Message { get; set; }
        public LogType LoggedType { get; set; }
        public override string ToString()
        {
            return string.Format("LogType: {0} Datetime: {1} Message: {2}", LoggedType, LoggedDateTime, Message);
        }
    }
    class Program
    {
        static void Main()
        {
            var logFatal = new Log
                               {
                                   LoggedDateTime = new DateTime(2011, 2, 22),
                                   Message = "Hi am a Fatal message",
                                   LoggedType = LogType.Fatal
                               };

            var logInfo = new Log
            {
                LoggedDateTime = new DateTime(2013, 2, 22),
                Message = "Hi I am a Info message",
                LoggedType = LogType.Info
            };

            var logError = new Log
            {
                LoggedDateTime = new DateTime(2010, 2, 22),
                Message = "Hi I am a Error message",
                LoggedType = LogType.Error
            };

            var logWarning = new Log
            {
                LoggedDateTime = new DateTime(2014, 2, 22),
                Message = "Hi I am a Warning message",
                LoggedType = LogType.Warn
            };
            List<Log> logs = new List<Log> { logWarning, logError, logInfo, logFatal };

            Console.WriteLine("Not Ordered");
            Console.WriteLine("");
            logs.ForEach(x=>Console.WriteLine(x.LoggedType));



            var orderedLogs = logs.OrderBy(x => x.LoggedType == LogType.Fatal)
                .ThenBy(x => x.LoggedType == LogType.Error)
                .ThenBy(x => x.LoggedType == LogType.Warn)
                .ThenBy(x => x.LoggedDateTime).ToList();

            Console.WriteLine("Ordered by logType fatal first and NOT WORKING");
            Console.WriteLine("");

            orderedLogs.ForEach(x=>Console.WriteLine(x.LoggedType));

            Console.WriteLine("");
            Console.WriteLine("Ordered by logType fatal first and NOT WORKING");//NOT WORKING
            List<Log> orderedFatal = logs.OrderBy(x => x.LoggedType == LogType.Fatal).ToList();
            orderedFatal.ForEach(x => Console.WriteLine(x.LoggedType));

            Console.WriteLine("");
            Console.WriteLine("Sorted by datetime AND WORKS"); //THIS IS THE ONLY ONE THAT WORKS
            logs.Sort((x,y)=>x.LoggedDateTime.CompareTo(y.LoggedDateTime));
            logs.ForEach(x => Console.WriteLine(x.LoggedDateTime));


            Console.Read();
        }
    }

Thanks for any suggestions

Answer 1

The problem is that false is ordered before true.
Thus first in your order come those that are not Fatal. Out of those first come those that are not Error etc.

You can use inequalities to make it work:

x => x.LoggedType != LogType.Fatal

etc.

or use OrderByDescending and ThenByDescending.

But I’d prefer to give an order of the enum:

public enum LogType : int
    {
        Fatal = 5,
        Error = 4,
        Warn = 3,
        Info = 2,
        Debug = 1,
        None = 0,
}

and then just use this value:

var orderedLogs = logs.OrderByDescending(x => x.LoggedType);