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c#dotnet-httpclienthttpexception
Kugel
Kugel

Reputation: 19814

How do I get StatusCode from HttpRequestException?

I'm probably missing something obvious here.

I'm using HttpClient which throws HttpRequestException that contains StatusCode in the Message string.

How can I access that StatusCode?

Edit: More info, I wrote this question in rush.

I'm using HttpClient to access another API within my WebApi project. Yes, I know why I'm calling EnsureSuccessStatusCode(). I want to propagate some errors downstream such as 404 and 403.

All I wanted was to consistently transform HttpRequestException into HttpResponseException using custom ExceptionFilterAttribute.

Unfortunately, HttpRequestException does not carry any extra info I could use besides the message. I was hoping to uncover StatusCode in raw (int or enum) form.

Looks like I can either:

  1. Use the message to switch the status code (bleh)
  2. Or create my version of EnsureSuccessStatusCode and throw exception that's actually usable.

Upvotes: 115

Views: 125378

Answers (8)

TanvirArjel
TanvirArjel

Reputation: 32069

From .NET 5.0, HttpRequestException has a StatusCode property which will have a value if the exception represents a non-successful result, otherwise null. So you can use as follows:

try
{
   // Your code
}
catch (HttpRequestException httpRequestException)
{
   if ((int)httpRequestException.StatusCode == 401)
   {
        // Show unauthorized error message
   }
   else 
   {
       // Other error message
   }
}

For more details are here

Upvotes: 34

ravi
ravi

Reputation: 1019

in .Net 6

    try
    {
        return await _httpClient.GetFromJsonAsync<YourType>("<url>", cancellationToken);
    }
    catch (HttpRequestException e) when (e.StatusCode == HttpStatusCode.NotFound)   
    {
        // handle 404
    }

Upvotes: 4

tigrou
tigrou

Reputation: 4516

If what you need is to extract status code from HttpRequestException (eg: in a application exception handler), look at answers from others.

Otherwise you might take a look at HttpClient.GetAsync() method. Unlike methods like HttpClient.GetStringAsync() (which return simple data type and thrown and exception if something goes wrong), that one return you a HttpResponseMessage object everytime, regardless request success or failure.

From there you can check status code :

var response = await client.GetAsync(...);
if (!response.IsSuccessStatusCode)
{
    var statusCode = response.StatusCode;
    //throw an exception or something similar
}

var responseText = await response.Content.ReadAsStringAsync();

Upvotes: 0

TheLegendaryCopyCoder
TheLegendaryCopyCoder

Reputation: 1832

For .Net Core 3.1 I could not make use of TanvirArjel or Lex Li's solution. So I went with manually calling the HttpClient's GetHttpAsync method and interrogating the Http status code myself. If the status code returns "OK" I process the HttpClient's Content property for the returned Html.

public async Task<string> GetHtml(string url)
{
    int retry = 3;

    while (retry > 0)
    {
        retry = retry - 1;

        try
        {   
            var result = await client.GetAsync(url);
            if (result.StatusCode != HttpStatusCode.OK)
            {
                switch (result.StatusCode)
                {
                    case HttpStatusCode.BadGateway:
                    case HttpStatusCode.BadRequest:
                    case HttpStatusCode.Forbidden:
                    case HttpStatusCode.ServiceUnavailable:
                    case HttpStatusCode.GatewayTimeout:
                        {
                            Global.Report($"CustomHttpClient: Temporary issue detected. Pausing to allow time to resolve.");
                            // Wait for temporary issue to resolve
                            await Task.Delay(120000);
                            continue;
                        }
                    default:
                        {
                            throw new Exception($"CustomHttpClient: Error {result.StatusCode}.");
                        }
                }
            }
            string response = await result.Content.ReadAsStringAsync();
            return response;
        }
        catch (Exception ex)
        {
            throw new Exception($"CustomHttpClient: Error downloading page => {url}. " + ex);
        }
    }

    throw new Exception($"CustomHttpClient: Temporary issue persists. Retries exhausted. Unable to download page => {url}.");
}

Upvotes: 0

Steve
Steve

Reputation: 1065

For what its worth, this guy did something clever: https://social.msdn.microsoft.com/Forums/vstudio/en-US/dc9bc426-1654-4319-a7fb-383f00b68def/c-httpresponsemessage-throws-exception-httprequestexception-webexception-the-remote-name?forum=csharpgeneral

In the case where I needed an exception status property, I can do this:

catch (HttpRequestException requestException)
{
    if (requestException.InnerException is WebException webException && webException.Status == WebExceptionStatus.NameResolutionFailure)
    {
        return true;
    }

    return false;
}

Upvotes: 34

Lex Li
Lex Li

Reputation: 63173

Status code was passed as part of a string to HttpRequestException so that you cannot recover it from such exceptions alone.

The design of System.Net.Http requires you to access HttpResponseMessage.StatusCode instead of waiting for the exception.

http://msdn.microsoft.com/en-us/library/system.net.http.httpresponsemessage(v=vs.110).aspx

If you are now following the Microsoft guide, make sure you understand clearly why it asks you to call HttpResponseMessage.EnsureSucessStatusCode. If you don't call that function, there should be no exception.

Upvotes: 50

Rastislav Bodorik
Rastislav Bodorik

Reputation: 23

This has worked for me

var response = ex.Response;
var property = response.GetType().GetProperty("StatusCode");
if ( property != null && (HttpStatusCode)property.GetValue(response) == HttpStatusCode.InternalServerError)

Upvotes: 1

Surender Singh Malik
Surender Singh Malik

Reputation: 295

As mentioned by others as well it's not a good practice to get the StatusCode from HttpRequestException, the same can be done beforehand with HttpResponseMessage.StatusCode after checking HttpResponseMessage.IsSuccessStatusCode

Anyhow if due to some constraint/requirement one has to read StatusCode, There can be two solution

  1. Extended the HttpResponseMessage with your custom exception explained here
  2. Hack on the HttpRequestException.ToString to get the StatusCode, As the message is a constant post fixed by StatusCode and Repharse.

Below is the code in System.Net.Http.HttpResponseMessage Where SR.net_http_message_not_success_statuscode ="Response status code does not indicate success: {0} ({1})."

public HttpResponseMessage EnsureSuccessStatusCode()
    {
        if (!this.IsSuccessStatusCode)
        {
            if (this.content != null)
            {
                this.content.Dispose();
            }
            throw new HttpRequestException(string.Format(CultureInfo.InvariantCulture, SR.net_http_message_not_success_statuscode, new object[]
            {
                (int)this.statusCode,
                this.ReasonPhrase
            }));
        }
        return this;
    }

Upvotes: 3

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