Config.cs

using System;
using System.Configuration;

namespace Util
{
    public static class Config
    {
        public static string GetSetting(string key) => ConfigurationManager.AppSettings[key];

        public static bool HasSetting(string key) => !string.IsNullOrEmpty(GetSetting(key));

        public static string GetSettingOrDefault(string key, string defaultValue) => HasSetting(key)
            ? GetSetting(key)
            : defaultValue;


        public static bool IsTrue(string key)
        {
            bool enabled;
            return GetSetting(key) != null && bool.TryParse(GetSetting(key), out enabled) && enabled;
        }

        public static int GetSettingAsIntOrDefault(string key, int defaultValue)
        {
            try
            {
                return HasSetting(key) ? int.Parse(GetSetting(key)) : defaultValue;
            }
            catch (FormatException fomatException)
            {
                throw new FormatException($"Invalid format for setting {key}, expected an int", fomatException);
            }
        }

        public static string GetSettingOrError(string key)
        {
            if (!HasSetting(key))
                throw new ConfigurationErrorsException($"Unable to find required config value with key {key}");

            return GetSetting(key);
        }
    }
}