How to resolve HTTP/1.1 400 Bad Request

It would be nice if there were some way of turning off "throw on non-success code" but if you catch WebException you can at least use the response:

using System;
using System.IO;
using System.Web;
using System.Net;

public class Test
{
    static void Main()
    {
        WebRequest request = WebRequest.Create("http://csharpindepth.com/asd");
        try
        {
            using (WebResponse response = request.GetResponse())
            {
                Console.WriteLine("Won't get here");
            }
        }
        catch (WebException e)
        {
            using (WebResponse response = e.Response)
            {
                HttpWebResponse httpResponse = (HttpWebResponse) response;
                Console.WriteLine("Error code: {0}", httpResponse.StatusCode);
                using (Stream data = response.GetResponseStream())
                using (var reader = new StreamReader(data))
                {
                    string text = reader.ReadToEnd();
                    Console.WriteLine(text);
                }
            }
        }
    }
}

You might like to encapsulate the "get me a response even if it's not a success code" bit in a separate method. (I'd suggest you still throw if there isn't a response, e.g. if you couldn't connect.)

If the error response may be large (which is unusual) you may want to tweak HttpWebRequest.DefaultMaximumErrorResponseLength to make sure you get the whole error.

So, I just ended up doing this, Interface:

[OperationContract]
[WebInvoke(Method = "POST",
           UriTemplate = "LoggingTest/{logID}/{logLevel}?errorCode={errorCodeInt}",
           BodyStyle = WebMessageBodyStyle.Bare)]
void LoggingTest(string logID, string logLevel, int errorCodeInt, Stream message);

Implementation:

public void LoggingTest(string logID, string logLevel, int errorCodeInt, Stream message)
    {
        switch (logLevel)
        {
            case "error":
                log.Error(errorCodeInt, message, null);
                break;
            case "warn":
                log.Warn(errorCodeInt, message, null);
                break;
            case "info":
                log.Info(errorCodeInt, message, null);
                break;
            case "debug":
                log.Debug(errorCodeInt, message, null);
                break;
        }
    }

And now it works. Must have something to do with the parameters being passed in the UriTemplate, because when I changed it to pass the parameters like so:

UriTemplate = "LoggingTest/{logID}/{logLevel}?errorCode={errorCodeInt}",

it started accepting the POST.

Edit 7/7: Here's the final JavaScript also:

jqueryPost('LoggingTest/LogID/debug?errorCode=0', { message: 'this is a test message'} ;

function jqueryPost(url, message) {
    $.post(url, message);
}