Owin Friendly Exceptions Middleware

A middleware that can translate exceptions into nice http resonses. This allows you to throw meaningfull exceptions from your framework, business code or other middlewares and translate the exceptions to nice and friendly http responses.

Installation

Install-package OwinFriendlyExceptions

See Troubleshooting for help with any installation errors

Plugins for different frameworks

Owin Friendly Exceptions is extensible and can work with frameworks that normally swallows exceptions.

See OwinFriendlyExceptions.Plugins for plugins to handle different frameworks (ASP.NET Web API etc...)

Example

using System;
using System.Net;
using Api.Exceptions;
using Api.Logic.Exceptions;
using Owin;
using OwinFriendlyExceptions;
using OwinFriendlyExceptions.Extensions;
using OwinFriendlyExceptions.Plugins.WebApi2;

namespace Api
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            // Use FriendlyExceptions before your other middlewares
            app.UseFriendlyExceptions(GetFriendlyExceptions(), new [] {new WebApi2ExceptionProvider()});

            // Then the rest of your application
            //app.UseCors(options);
            //app.UseWelcomePage();
            //app.UseWebApi(config)
        }

        private ITransformsCollection GetFriendlyExceptions()
        {
            return TransformsCollectionBuilder.Begin()

                .Map<ExampleException>()
                .To(HttpStatusCode.BadRequest, "This is the reasonphrase",
                    ex => "And this is the response content: " + ex.Message)

                .Map<SomeCustomException>()
                .To(HttpStatusCode.NoContent, "Bucket is emtpy", ex => string.Format("Inner details: {0}", ex.Message))

                .Map<EntityUnknownException>()
                .To(HttpStatusCode.NotFound, "Entity does not exist", ex => ex.Message)

                .Map<InvalidAuthenticationException>()
                .To(HttpStatusCode.Unauthorized, "Invalid authentication", ex => ex.Message)

                .Map<AuthorizationException>()
                .To(HttpStatusCode.Forbidden, "Forbidden", ex => ex.Message)

            .Done();
        }
    }
}

Web Api 2 plugin

Installation:

1. Install-package OwinFriendlyExceptions.Plugins.WebApi2
2. app.UseFriendlyExceptions(exceptionsToHandle, new [] {new WebApi2ExceptionProvider()});
3. config.Services.Replace(typeof(IExceptionHandler), new WebApi2ExceptionHandler(exceptionsToHandle)); Install the package, and supply the WebApi Exception Provider to the OwinFriendlyExceptions extension method. In order for the Plugin to get swalloed wexceptions you have to replace the ExcepionHandler service in Web Api. The plugin takes a list of which exceptions we can handle, so WebApi can still take care of unhandled exceptions for you.

Troubleshooting

When installing the Web Api Plugin, sometimes your System.Web.Http reference will mismatch. Use this Package Manager Console command to fix your Assembly Bining redirect: Get-Project YourProjectReferencingOwinFriendlyExceptions | Add-BindingRedirect

Contribute

Contributions are welcome. Just open an Issue or submit a PR.

Contact

You can reach me at @bigCheeseAnders or via my blog: ideasof.andersaberg.com