Creating a Web API to work with XML requests

by Jan de Vries in  ,

For a project on the side I’m creating a Web API which has to parse XML requests in a POST. The first method I’ve written looks like this:

[HttpPost]
public HttpResponseMessage IndexPost(RequestModel requestMessage)
{
	return new HttpResponseMessage(HttpStatusCode.Accepted) { Content = new StringContent("This is the POST API response from BusinessPartner!") };
}

To test the new API I’m using the Postman Chrome plugin. With this plugin you are able to send requests to an endpoint and see what the response is. Of course you can also use Fiddler for this, but I like the user experience of Postman a bit more.

There were a few problems I encountered during the development of the Web API.

The first problem was this error:

{
    "message": "An error has occurred.",
    "exceptionMessage": "No MediaTypeFormatter is available to read an object of type 'RequestModel' from content with media type 'text/plain'.",
    "exceptionType": "System.InvalidOperationException",
    "stackTrace": "   at System.Net.Http.HttpContentExtensions.ReadAsAsync[T](HttpContent content, Type type, IEnumerable`1 formatters, IFormatterLogger formatterLogger)\r\n   at System.Net.Http.HttpContentExtensions.ReadAsAsync(HttpContent content, Type type, IEnumerable`1 formatters, IFormatterLogger formatterLogger)\r\n   at System.Web.Http.ModelBinding.FormatterParameterBinding.ReadContentAsync(HttpRequestMessage request, Type type, IEnumerable`1 formatters, IFormatterLogger formatterLogger)\r\n   at System.Web.Http.ModelBinding.FormatterParameterBinding.ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken)\r\n   at System.Web.Http.Tracing.Tracers.FormatterParameterBindingTracer.<>c__DisplayClass3.<executebindingasync>b__1()\r\n   at System.Web.Http.Tracing.ITraceWriterExtensions.TraceBeginEndAsync(ITraceWriter traceWriter, HttpRequestMessage request, String category, TraceLevel level, String operatorName, String operationName, Action`1 beginTrace, Func`1 execute, Action`1 endTrace, Action`1 errorTrace)\r\n   at System.Web.Http.Tracing.Tracers.FormatterParameterBindingTracer.ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken)\r\n   at System.Web.Http.Controllers.HttpActionBinding.<>c__DisplayClass1.<executebindingasync>b__0(HttpParameterBinding parameterBinder)\r\n   at System.Linq.Enumerable.WhereSelectArrayIterator`2.MoveNext()\r\n   at System.Threading.Tasks.TaskHelpers.IterateImpl(IEnumerator`1 enumerator, CancellationToken cancellationToken)"
}

This was quite surprising as I thought I was sending a proper request which could be serialized. For reference, I was sending a POST request to https://localhost:11210/api/businesspartnerapi/ in this format:

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