Raygun4Net automatic Breadcrumb logging with ASP.NET MVC

RaygunBreadcrumbAttribute.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Web.Mvc;
using Mindscape.Raygun4Net;
using Mindscape.Raygun4Net.Breadcrumbs;

namespace Raygun.Examples
{
  public class RaygunBreadcrumbAttribute : ActionFilterAttribute
  {
    public string CustomMessage { get; set; }

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
      var parameters = filterContext.ActionParameters;

      var crumb = new RaygunBreadcrumb();
      var controllerType = filterContext.ActionDescriptor.ControllerDescriptor.ControllerType;

      crumb.Message = CustomMessage ?? $"Executing {controllerType.Name}:{filterContext.ActionDescriptor.ActionName}";
      crumb.Level = RaygunBreadcrumbLevel.Debug;
      crumb.ClassName = controllerType.FullName;
      crumb.MethodName = filterContext.ActionDescriptor.ActionName;

      if (parameters != null)
      {
        foreach (var parameter in parameters)
        {
          crumb.CustomData.Add(parameter.Key, parameter.Value.ToDisplayString() ?? "NULL");
        }
      }

      RaygunClient.RecordBreadcrumb(crumb);

      base.OnActionExecuting(filterContext);
    }
  }

  public static class Ext
  {
    public static string ToDisplayString<T>(this T instance) where T : class
    {
      if (instance == null)
        return string.Empty;

      Type instanceType = instance.GetType();
      if (instanceType.IsPrimitive || instanceType == typeof (string))
      {
        return instance.ToString();
      }

      var strListType = typeof (List<string>);
      var strArrType = typeof (string[]);

      var arrayTypes = new[] {strListType, strArrType};
      var handledTypes = new[] {typeof (int), typeof (long), typeof (string), typeof (bool), typeof (DateTime), typeof (double), typeof (decimal), strListType, strArrType};

      var validProperties = instanceType
        .GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic)
        .Where(prop => handledTypes.Contains(prop.PropertyType))
        .Where(prop => prop.GetValue(instance, null) != null)
        .ToList();

      return string.Format("{0}[{1}]", instanceType.Name,
        string.Join(
          ", ",
          validProperties.Select(prop => string.Format("{0}: {1}",
            prop.Name,
            (arrayTypes.Contains(prop.PropertyType) ? string.Join("|", (IEnumerable<string>) prop.GetValue(instance, null)) : prop.GetValue(instance, null))))
          )
        );
    }
  }
}