c# - REST seems to reject JSON POST -

i'm trying post data in json format server rejecting it. works if post in xml , reply in either xml or json.

the contract is

[servicecontract] public interface iservice {     // 1 string data     [operationcontract]     [webinvoke(         bodystyle = webmessagebodystyle.bare,         method = "post",         responseformat = webmessageformat.xml,         uritemplate = "data")]     string datapost(hidden param); }  // if compilation error, add // system.runtime.serialization references [datacontract(name = "hidden", namespace = "")] public class hidden {     [datamember]     public string id { get; set; } } 

the implementation is

public class service : iservice {     public string datapost(hidden param)     {         console.writeline("datapost " + param.id);         return "datapost said " + param.id;     } } 

on client side, run of mill standard stuff.

namespace client { enum httpverb {     get,     post,     put,     delete };  class restclient {     // properties     public string endpoint { get; set; }     public httpverb method { get; set; }     public string contenttype { get; set; }     public string paramdata { get; set; }     public string postdata { get; set; }      // methods     public string makerequest()     {         var responsevalue = string.empty;         string ep = endpoint;         if (!string.isnullorempty(paramdata))             ep += "/" + paramdata;         var request = (httpwebrequest)webrequest.create(ep);         request.method = method.tostring();         request.contentlength = 0;         request.contenttype = contenttype;          // postdata parameters         if (!string.isnullorempty(postdata) && method == httpverb.post)         {             var encoding = new utf8encoding();             var bytes = encoding.getencoding("iso-8859-1").getbytes(postdata);             request.contentlength = bytes.length;             using (var poststream = request.getrequeststream())             {                 poststream.write(bytes, 0, bytes.length);             }             if (postdata.substring(0, 1) != "<")                 request.contenttype = "application/json";             console.writeline("content type " + request.contenttype.tostring());         }          // send request , response         using (var response = (httpwebresponse)request.getresponse())         {             // did work?             if (response.statuscode != httpstatuscode.ok)             {                 var message = string.format("request failed.  received http {0}", response.statuscode);                 throw new applicationexception(message);             }              // response             using (var responsestream = response.getresponsestream())             {                 if (responsestream != null)                 {                     using (var reader = new streamreader(responsestream))                     {                         responsevalue = reader.readtoend();                     }                 }             }         }         return responsevalue;     }      void talkto(         httpverb in_method,         string in_endpoint,         string in_paramdata,         string in_postdata)     {         method = in_method;         endpoint = in_endpoint;         contenttype = "text/xml";         paramdata = in_paramdata;         postdata = in_postdata;          try         {             string response = makerequest();             console.writeline("endpoint: " + endpoint);             console.writeline("resp    : " + response);             console.writeline();         }         catch (system.net.webexception e)         {             console.writeline("endpoint: " + endpoint);             console.writeline("failed  : " + e.message);         }     }      static void main(string[] args)     {         restclient me = new restclient();         string endpointprefix = @"http://localhost:8000/";         me.talkto(             httpverb.post,             endpointprefix + "data",             "",             "<hidden><id>xml works</id></hidden>");          string post = "{\"id\":\"json works\"}";         console.writeline("json string [" + post + "]");         me.talkto(             httpverb.post,             endpointprefix + "data",             "",             post);          console.writeline("press <enter> terminate");         console.readline();     } } } 

on client side, i'm getting

content type text/xml endpoint: http://localhost:8000/data resp    : <string xmlns="http://schemas.microsoft.com/2003/10/serialization/">datapost said xml works</string>  json string [{"id":"json works"}] content type application/json endpoint: http://localhost:8000/data failed  : remote server returned error: (400) bad request. press <enter> terminate 

when @ help, says json format allowable when try it, falls over. trace sever debug seems imply ignoring application/json , assuming xml.

exception: system.runtime.serialization.serializationexception, mscorlib, version=4.0.0.0, culture=neutral, publickeytoken=b77a5c561934e089  message: there error checking start element of object of type system.string. data @ root level invalid. line 1, position 1.  last few lines of stack trace system.runtime.serialization.xmlobjectserializer.isstartobjecthandleexceptions(xmlreaderdelegator reader) system.runtime.serialization.datacontractserializer.isstartobject(xmldictionaryreader reader) system.servicemodel.dispatcher.singlebodyparametermessageformatter.readobject(message message) 

all examples i've looked @ on , other sites don't add special not working because i'm using vs2013 express?

edit happens on vs2013 web express

edit2 doesn't isolated express versions - i've tried on vs2010 professional. still using xmlobjectserializer parse json , failing miserably.

the fix no convert postdata bytes

        if (!string.isnullorempty(postdata) && method == httpverb.post)         {             if (postdata.substring(0, 1) != "<")                 request.contenttype = "application/json";             console.writeline("content type " + request.contenttype.tostring());             request.contentlength = postdata.length;             using (var poststream = new streamwriter(request.getrequeststream()))             {                 poststream.write(postdata);             }         }