c# - how to return json error msg in asp.net web api? -

i return json errormessage @ moment in fiddler cannot see in json panel:

string error = "an error happened"; jsonresult jsonresult = new jsonresult {      data = error,      jsonrequestbehavior = jsonrequestbehavior.allowget }; response = request.createresponse(httpstatuscode.badrequest, jsonresult.data); 

how this?

a few points:

if you're looking return error response containing simple error message, web api provides createerrorresponse method that. can do:

return request.createerrorresponse(httpstatuscode.badrequest,                                     "an error happened"); 

this result in following http response (other headers omitted brevity):

http/1.1 400 bad request content-type: application/json; charset=utf-8 content-length: 36  {"message":"an error happened"} 

if want return custom object instead, use request.createresponse doing, don't use mvc jsonresult. instead, pass object directly createresponse:

var myerror = new {     data = "an error happened",     otherdetails = "foo bar baz" };  return request.createresponse(httpstatuscode.badrequest, myerror); 

now, doing you're not getting json server. important realize web api uses content type negotiation determine format use when sending response back. means, looks @ accept header sent client request. if accept header contains application/xml, example, web api return xml. if header contains application/json return json. so, should check client sending correct accept header.

that said, there ways force web api return data in specific format if want. can @ method level using different overload of createresponse specifies content type:

return request.createresponse(httpstatuscode.badrequest, myerror,      new system.net.http.headers.mediatypeheadervalue("application/json")); 

alternatively, can remove xml formatter configuration altogether in webapiconfig file:

config.formatters.remove(config.formatters.xmlformatter); 

this force web api use json regardless of client asks for.