Web API unsupported media type when uploading - charset not passed

Question

I'm developing a new web API and currently integrating (re-writing) the legacy API to work with the new one. However I'm having issues with the Excel templates. Every time I try do a POST I get a 415 unsupported media type error.

I have managed to make it work so I know my code is fine the problem is when I use the templates it sets the content type in the header to:

Content-Type: application/xml;

However, if I change the template to send:

Content-Type: application/xml; charset=utf-8

It works as I would expect. The problem is I can't change the templates in production. I have to make my code work with the templates as they are.

Answer 1

The issue here seems to be with the ending ; in the case of Content-Type: application/xml;...Web API relies on System.Net.Http library for getting request headers and this library gives a null for HttpRequestMessage's Content.Headers.ContentType in this case and Web API sees that Content-Length is greater than 0 but no Content-Type header and hence returns a 415 Unsupported Media Type.

Following a workaround that I have tried and that works (I am using a Owin middleware as this would be a stage where I could modify the raw request header before the System.Net.Http library's parsing takes place...)

public class FixContentTypeHeader : OwinMiddleware
{
    public FixContentTypeHeader(OwinMiddleware next) : base(next) { }

    public override async Task Invoke(IOwinContext context)
    {
        // Check here as requests can or cannot have Content-Type header
        if(!string.IsNullOrWhiteSpace(context.Request.ContentType))
        {
            MediaTypeHeaderValue contentType;

            if(!MediaTypeHeaderValue.TryParse(context.Request.ContentType, out contentType))
            {
                context.Request.ContentType = context.Request.ContentType.TrimEnd(';');
            }
        }

        await Next.Invoke(context);
    }
}

---

public void Configuration(IAppBuilder appBuilder)
{
    appBuilder.Use<FixContentTypeHeader>();