1

I need to do a Web Api that return an HTML content. This is my code:

 [HttpGet]
    public HttpResponseMessage test()
    {
        var response = new HttpResponseMessage(HttpStatusCode.OK);
        response.Content = new StringContent("<html><body>HELLO</body></html>");
        response.Content.Headers.ContentType = new MediaTypeHeaderValue("text/html");            
        return response;
    }

When I am in debug it works fine. But if I publish the web app on a server (Windows Server 2012, IIS 8) this error return:

<Error>
<script/>
<script id="tinyhippos-injected"/>
<Message>An error has occurred.</Message>
<ExceptionMessage>
The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'.
</ExceptionMessage>
<ExceptionType>System.InvalidOperationException</ExceptionType>
<StackTrace/>
<InnerException>
<Message>An error has occurred.</Message>
<ExceptionMessage>
Type 'System.Net.Http.StringContent' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. If the type is a collection, consider marking it with the CollectionDataContractAttribute. See the Microsoft .NET Framework documentation for other supported types.
</ExceptionMessage>
<ExceptionType>
System.Runtime.Serialization.InvalidDataContractException
</ExceptionType>
<StackTrace>
at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.ThrowInvalidDataContractException(String message, Type type) at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.CreateDataContract(Int32 id, RuntimeTypeHandle typeHandle, Type type) at System.Runtime.Serialization.DataContract.DataContractCriticalHelper.GetDataContractSkipValidation(Int32 id, RuntimeTypeHandle typeHandle, Type type) at System.Runtime.Serialization.XmlObjectSerializerContext.GetDataContract(RuntimeTypeHandle typeHandle, Type type) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiType(XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle objectTypeHandle, Type objectType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerialize(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.InternalSerializeReference(XmlWriterDelegator xmlWriter, Object obj, Boolean isDeclaredType, Boolean writeXsiType, Int32 declaredTypeID, RuntimeTypeHandle declaredTypeHandle) at WriteHttpResponseMessageToXml(XmlWriterDelegator , Object , XmlObjectSerializerWriteContext , ClassDataContract ) at System.Runtime.Serialization.ClassDataContract.WriteXmlValue(XmlWriterDelegator xmlWriter, Object obj, XmlObjectSerializerWriteContext context) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.WriteDataContractValue(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithoutXsiType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle declaredTypeHandle) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__22.MoveNext()
</StackTrace>
</InnerException>
</Error>

How can I resolve this issue?

Passa4
  • 11
  • 2
  • 1
    What is a `MyStringContent`? – mason May 24 '18 at 12:23
  • Is `MyStringContent` some sort of derived class? Anyway see https://stackoverflow.com/questions/26822277/return-html-from-asp-net-web-api and https://stackoverflow.com/questions/12240713/put-content-in-httpresponsemessage-object for some working examples. – ADyson May 24 '18 at 12:27
  • `MyStringContent` was a test. I edited the question with the class `StringContent`. The error returned is the same. – Passa4 May 24 '18 at 13:34
  • From the error, it seems something is trying to turn your response into XML instead of HTML, and of course that won't work very well. Are you trying to view it in a browser window? Web API often tries to serialise to XML automatically in that scenario. What happens if you use a tool like PostMan to visit the URL instead? – ADyson May 24 '18 at 14:54

0 Answers0