Passing XDocument as message content

In the wcf version I was passing XDocuments back and forth between my server & httpclient by doing

new HttpRequestMessage() {
  Content = new StringContent(doc.ToString())
}

and then usign ReadAsStreamAsync() to pull it out on the server side

As of the beta this no longer works. What is the recommended way to do this?

Re: Passing XDocument as message content

Can you elaborate more as to what kind of behavior are you seeing on the Server side?

I am guessing you are trying to read the request's content at anAction of a controller...how does your Action look like?

Thanks, Kiran

Re: Passing XDocument as message content

You need to set the encoding and mediaType parameters on StringContent. Setting the mediaType parameter to "application/xml" should work. By default the media type is "text/plain."

Re: Passing XDocument as message content

When I call the client like

var post = client.PostAsync("http://localhost:32510/api/something",
                             new StringContent(doc.ToString()));

I am not able to break into any of my code on the server side, instead I just get a 500

 var responseDoc = post.Result.Content.ReadAsStringAsync().Result;

It looks like the response comes back as a JSON serialized exception?

{"ExceptionType":"System.InvalidOperationException","Message":"No 'MediaTypeFormatter' is available to read an object of type 'HttpRequestMessage' with the media type 'text\/plain'.","StackTrace":"   at System.Net.Http.ObjectContent.SelectAndValidateReadFormatter(Boolean acceptNullFormatter)\u000d\u000a   at System.Net.Http.ObjectContent.ReadAsyncInternal[T](Boolean allowDefaultIfNoFormatter)\u000d\u000a   at System.Web.Http.ModelBinding.RequestContentReader.ReadWholeBodyAsync(HttpActionContext actionContext, Type modelType)\u000d\u000a   at System.Web.Http.ModelBinding.RequestContentReader.ReadContentAsync(HttpActionContext actionContext)\u000d\u000a   at System.Web.Http.ModelBinding.DefaultActionValueBinder.BindValuesAsync(HttpActionContext actionContext, CancellationToken cancellationToken)\u000d\u000a   at System.Web.Http.ApiController.<>c__DisplayClass3.b__0()\u000d\u000a at System.Web.Http.ApiController.ExecuteAsync(HttpControllerContext controllerContext, CancellationToken cancellationToken)\u000d\u000a at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsyncInternal(HttpRequestMessage request, CancellationToken cancellationToken)\u000d\u000a at System.Web.Http.Dispatcher.HttpControllerDispatcher.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)"}

Re: Passing XDocument as message content

Yes, the default formatter is the JsonFormatter. Unless you specify media types in your Accept header, you should expect a JSON response.

Try using:

new StringContent(doc.ToString(), System.Text.Encoding.UTF8, "application/xml");

Re: Passing XDocument as message content

** EDIT: nevermind this, I see another thread answers this question**

I had tried doing that but then on the server side I get a NRE because request.Content is null

public HttpResponseMessage SomeApiMethod(HttpRequestMessage request)
        {
            var doc = XDocument.Parse(request.Content.ReadAsStringAsync().Result);

}

Re: Passing XDocument as message content

Also, keep in mind that calling .Result immediately can lead to deadlocks. I don't remember the link at the moment.

Re: Passing XDocument as message content

Ah, I see. Model binding isn't working on HttpRequestMessage in the method parameters in the beta, though I think that is coming again. Use this.Request property on the ApiController. See this thread: http://forums.asp.net/t/1770894.aspx/1?request+Content+ReadAsync+Result+returns+null.

Re: Passing XDocument as message content

really, that is scary, what's the correct way?

Re: Passing XDocument as message content

chrisortman

really, that is scary, what's the correct way?

In .NET 4.5, you should use the async/await keywords. In .NET 4.0, you should probably go with the .ContinueWith() to continue your execution chain. Henrik has posted examples.

Re: Passing XDocument as message content

public Task<HttpResponseMessage> SomeApiMethod()
        {
            return Request.Content.ReadAsStreamAsync().ContinueWith(s =>
            {
                var doc = XDocument.Load(s.Result);

Throws: Cannot access a closed Stream, but ReadAsString() works fine.

Re: Passing XDocument as message content

That sounds like a bug. It shouldn't have closed if it hasn't been read.

Re: Passing XDocument as message content

It would be helpful if you could past the entire Action method here. I say this because, a similar scenario like yours works for me:

[HttpPost]
        public Task<string> TestActionReadingAsStream()
        {
            return Request.Content.ReadAsStreamAsync().ContinueWith<string>(tsk =>
                {
                    string value = null;

                    using (StreamReader reader = new StreamReader(tsk.Result))
                    {
                        value = reader.ReadToEnd();
                    }

                    return value;
                });
        }