Develop Reference

How to pass error details when using StatusCodePagesWithRedirects in ASP.NET Core

I have an ASP.NET Core application and I'm attempting to handle HTTP responses with status codes between 400 and 599 by using UseStatusCodePagesWithRedirects.
In Startup.cs I've added the following:
app.UseStatusCodePagesWithRedirects("/Error");
My Error controller is empty except for the following action (which was taken from the default scaffolded Home controller):
[Route("Error")]
[ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
public IActionResult Error()
{
return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier });
}
This works perfectly when I call return new BadRequestResult(); or return NotFound(); from one of my controllers, but when I try to return an error with more detail (such as including an error object) the controller action is never called and the body of the response is displayed on screen as plaintext instead. As an example, the following statement does not trigger the Error controller:
context.Result = new BadRequestObjectResult({ Errors = errors });
If I use the following statement instead, the middleware is correctly called:
context.Result = new BadRequestResult();
This appears to be working as designed, as the documentation states that UseStatusCodePagesWithRedirects "checks for responses with status codes between 400 and 599 that do not have a body" (emphasis mine) and the source code backs this up.
I want to include more information on my error page (such as user friendly error messages where appropriate) but I can't figure out how I can pass the data across effectively using the middleware since I'm trying to avoid my controllers knowing too much about how errors are handled so that the logic can be contained in one place and potentially changed later.
Is there a way to return a HTTP error that has additional information but will still get picked up by UseStatusCodePagesWithRedirects?

This is not how the exception handling middleware works. I'm not sure what you're doing exactly, but it looks like you're attempting to return BadRequest from middleware or an action filter. If you want to intercept some error there, you should simply allow the exception to bubble up (or throw one), not return a response, as that way, you'll keep the context of what happened.
Inside your error action, you can use HTTP feature interfaces to get the data you're looking for then. For example, there's:
var exceptionHandlerPathFeature = HttpContext.Features.Get<IExceptionHandlerPathFeature>();
If there was an exception, you can access it then via exceptionHandlerPathFeature.Error. There's also IStatusCodeReExecuteFeature, which you can use to get the original URL of the request for things like 404s:
var statusCodeReExecuteFeature = HttpContext.Features.Get<IStatusCodeReExecuteFeature>();
if (statusCodeReExecuteFeature != null)
{
OriginalURL =
statusCodeReExecuteFeature.OriginalPathBase
+ statusCodeReExecuteFeature.OriginalPath
+ statusCodeReExecuteFeature.OriginalQueryString;
}
Source
Depending on exactly what you're doing, there might be other ways as well.

The below is not exactly what you need (passing an error details/an error object) but it seems like you can pass an error code, at least in ASP.NET Core.
If you look at the documentation for UseStatusCodePagesWithRedirects, it says that you can pass a status code, since the url template may contain such parameter:
app.UseStatusCodePagesWithRedirects("/MyStatusCode?code={0}");
Then in your MyStatusCode.cshtml you can intercept it like:
#{
var codeStr = Context.Request.Query.ContainsKey("code") ? Context.Request.Query["code"].ToString() : "-1";
}

Is there a way to make Refit convert to different model based on Http return code?

I need some help with Refit...
I'm building an Xamarin.Android app, and I'm using Refit to make some network calls to some endpoints.
Based on the normal functionalitty of Refit, we can make it convert the response to a model or a list of models we want:
[Get("/Racas.aspx")]
Task<List<Raca>> GetRacas([AliasAs("token")] string token);
This works as intended, but, since the API returns a different model other than "Raca" when there is any errors, how can I convert it properly?
This is a basic example, only a Get on the endpoint, that will return me a list of the resource with HTTP 200, OR, if anything goes wrong, the server will return me a model called "Mensagem" rather than "Raca" with HTTP 5xx, or 4xx...
How can I proceed with it? The GetRacas() should be able to convert to, based on HTTP code:
Task<List<Raca>> GetRacas()
and
Task<Mensagem> GetRacas()
I'm calling the Tasks of refit like this:
await GetApiService().GetRacas(currentUser.Token).ContinueWith(data =>
{
if (data.IsCompleted && data.Status == TaskStatus.RanToCompletion)
{
...
}
...
});
I appreciate any help!
Thanks

WordPress WooCommerce ASP.net API WebHookHandler: The WebHook request must contain an entity body formatted as HTML Form Data

I am trying to create a WebHookHandler for Webhooks send from WordPress WooCommerce in ASP.NET C#.
I started with creating a ASP.NET C# Azure API App WebApplication Project and adding the relevant references (Microsoft.AspNet.WebHooks.Common, Microsoft.AspNet.WebHooks.Receivers, Microsoft.AspNet.WebHooks.Receivers.WordPress). Added the WebHookConfig, WordPressWebHookHandler and registered the WebHookConfig in the GlobalAsax.
I then published the application as an Azure App Service.
My WordPressWebHookHandler is still the default of the examples and looks like this:
public class WordPressWebHookHandler : WebHookHandler
{
public override Task ExecuteAsync(string receiver, WebHookHandlerContext context)
{
// make sure we're only processing the intended type of hook
if("WordPress".Equals(receiver, System.StringComparison.CurrentCultureIgnoreCase))
{
// todo: replace this placeholder functionality with your own code
string action = context.Actions.First();
JObject incoming = context.GetDataOrDefault<JObject>();
}
return Task.FromResult(true);
}
}
When testing a User Creation WebHook in WooCommerce I can see the request in the log as below.
But unfortunately it is never received while debugging and I see below error.
I am thinking maybe I need a custom WebHook instead of the WordPress specific one as this is a WooCommerce Webhook. Or possibly it is handled wrong in the routing and ends up in another controller.
Any help is much appreciated.

Your WebHookReceiver is wrong
There is a mismatch of expecting HTML Form Data, when in fact it should be expecting JSON.
WordPressWebHookHandler is still the default
This is what is causing your error. If you look at the WordPressWebHookReceiver, the ReceiveAsync() method implementation, calls out to ReadAsFormDataAsync() method, which is not what you want, as your Content-Type is json. So, you want to be doing ReadAsJsonAsync().
Solution: Don't use the WordPressWebHookReceiver and switch it to another one that will call ReadAsJsonAsync().
Looking at the code
I am thinking maybe I need a custom WebHook instead of the WordPress specific one as this is a WooCommerce Webhook.
You had the right idea, so I dug up some of the code to explain exactly why this was happening.
The code block below is the ReceiveAsync() method that is overridden in the WordPressWebHookReceiver. You can see that it is calling the ReadAsFormDataAsync() which is not what you want...
public override async Task<HttpResponseMessage> ReceiveAsync(
string id, HttpRequestContext context, HttpRequestMessage request)
{
...
if (request.Method == HttpMethod.Post)
{
// here is what you don't want to be called
// you want ReadAsJsonAsync(), In short, USE A DIFFERENT RECEIVER.
NameValueCollection data = await ReadAsFormDataAsync(request);
...
}
else
{
return CreateBadMethodResponse(request);
}
}
A quick search through the repository for classes that call the ReadAsJsonAsync() method, shows that the following recievers implement it:
DynamicsCrmWebHookReceiver
ZendeskWebHookReceiver
AzureAlertWebHookReceiver
KuduWebHookReceiver
MyGetWebHookReceiver
VstsWebHookReceiver
BitbucketWebHookReceiver
CustomWebHookReceiver
DropboxWebHookReceiver
GitHubWebHookReceiver
PaypalWebHookReceiver
StripeWebHookReceiver
PusherWebHookReceiver
I assumed that the CustomWebHookReceiver would fit your requirements, so can grab the NuGet here. Otherwise you can implement your own, or derive it from this class, etc.
Configuring a WebHook Recevier
(Copied from the Microsoft Documentation)
Microsoft.AspNet.WebHooks.Receivers.Custom provides support for
receiving WebHooks generated by ASP.NET WebHooks
Out of the box you can find support for Dropbox, GitHub, MailChimp,
PayPal, Pusher, Salesforce, Slack, Stripe, Trello, and WordPress but
it is possible to support any number of other providers
Initializing a WebHook Receiver
WebHook Receivers are initialized by registering them, typically in
the WebApiConfig static class, for example:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
...
// Load receivers
config.InitializeReceiveGitHubWebHooks();
}
}

There is a problem with the data format that you send in your request. You must use format of HTML Form as your error message said.
Proper POST data format is described here: How are parameters sent in an HTTP POST request?
Don't forget to set Content-Length header and correct Content-Type if your library doesn't do it. Usually the content type is application/x-www-form-urlencoded.

I would like to make some additions to Svek's answer as I now got my Proof-of-concept completed and understand a bit more about the receivers.
His answer pointed me in the right direction, but needs a little addition.
WordpressWebHookReceiver
Can take in Wordpress Webhooks of type HttpPost. This does not work with Woocommerce as Woocommerce sends Json Webhook messages and will fail the HttpPost validation which is build into the WordpressWebHookReceiver class.
CustomWebHookReceiver
Can take in custom ASP.NET Webhooks. The custom ASP.NET webhooks have a specific partner for validation which includes but is not limited to the 'ms-signature'. Even adding the header will not suffice as the signature is also used in a different way from out of the box Woocommerce to encrypt the message. Basically coming to a point that you can't integrate Woocommerce with the CustomWebHookReceiver without changing the Webhook classes of Woocommerce.
GenericWebHookReceiver
This is the receiver you want, which accepts basically a generic set of Json data and will be able to use the "code" query parameter to verify the secret which you can add in the web.config of your asp.net api application. I used this receiver to finish the Proof-of-concept and got both the signature validation as well as the deciphering of the message working right of the bat.
My basic class which I will start to build into a real solution can be viewed below and changes the JObject into a dynamic object in the methods I call from the class. As you can see I have two methods currently added, one for the customer create and one for the order create to call the respective methods which do an insert into Dynamics 365 (former CRM).
public class GenericJsonWebHookHandler : WebHookHandler
{
public GenericJsonWebHookHandler()
{
this.Receiver = "genericjson";
}
public override Task ExecuteAsync(string generator, WebHookHandlerContext context)
{
var result = false;
try
{
// Get JSON from WebHook
var data = context.GetDataOrDefault<JObject>();
if(context.Id != "crcu" && context.Id != "cror")
return Task.FromResult(true);
if (context.Id == "crcu")
{
result = WoocommerceCRMIntegrations.Entities.Contact.CreateContactInCRM(data);
}
else if (context.Id == "cror")
{
result = WoocommerceCRMIntegrations.Entities.Order.CreateOrderInCRM(data);
}
}
catch (Exception ex)
{
result = false;
}
return Task.FromResult(result);
}
}

ASP.NET - setting status code in controller response

I am a little bit confused sending specific status codes in responses from Web API controllers. Here is example of a simple controller method:
public IHttpActionResult GetDeliveryMethods()
{
if (AuthenticationControl)
{
return Ok(db.DeliveryMethods);
}
else
return StatusCode(HttpStatusCode.Unauthorized);
}
Well, "AuthenticationControl" represents some procedure checking, if a client can get data from the server. Whole method works well, but when I get back a response from the server status code is always 200 OK.
I don't understand why, this declaration of responses and status codes is also in main controller template in VS.
What I have to do to send my declaration of status code in response?

Return HTTPResoponse instead of your current return type.
This allows you to set HTTP status codes

How do I associate some custom data with current HttpRequest?

I need to somehow attach my custom data to the HttpRequest being handled by my IIS custom modules - so that code that runs in earlier stages of IIS pipeline attaches an object and code that runs in later stages can retrieve the object and use it and no other functionality of IIS pipeline processing is altered by adding that object.
The data needs to persist within one HTTP request only - I don't need it to be stored between requests. I need it to be "reset" for each new request automatically - so that when a new request comes it doesn't contain objects my code attached to the previous request.
Looks like HttpContext.Items is the way to go, although MSDN description of its purpose is not very clear.
Is using HttpContext.Current.Items the way to solve my problem?

This should work - I have done this in a project before.
I have a class which has a static property like this -
public class AppManager
{
public static RequestObject RequestObject
{
get
{
if (HttpContext.Current.Items["RequestObject"] == null)
{
HttpContext.Current.Items["RequestObject"] = new RequestObject();
}
return (RequestObject)HttpContext.Current.Items["RequestObject"];
}
set { HttpContext.Current.Items["RequestObject"] = value; }
}
}
And then RequestObject contains all my custom data so then in my app I can do
AppManager.RequestObject.CustomProperty
So far I have not come across any issues in the way HttpContext.Items works.