c# - Return JSON when Handling error in Web API -

i have created web api accepts 4 input parameters used in querying oracle database , returns result in json format. trying handle exception in uri if there input parameter missing or in wrong format . returning in json "error":"room cannot empty or null" if room in uri empty room=&dob_gt=01-sep-05&dob_lt=30-dec-06&status_type=cmplt

public class tgsdatacontroller : apicontroller { [httpget] public httpresponsemessage getdetails(string room, datetime dob_gt, datetime dob_lt, string status_type) {     if (string.isnullorempty(room))     {         var resp = new httpresponsemessage()         {             content = new stringcontent("room cannot empty or null")         };         resp.content.headers.contenttype = new mediatypeheadervalue("application/json");         return resp;     }     list<oracleparameter> prms = new list<oracleparameter>();     list<string> selectionstrings = new list<string>();     prms.add(new oracleparameter("room", oracledbtype.varchar2, room, parameterdirection.input));     prms.add(new oracleparameter("dob_gt", oracledbtype.date, dob_gt, parameterdirection.input));     prms.add(new oracleparameter("dob_lt", oracledbtype.date, dob_lt, parameterdirection.input));     prms.add(new oracleparameter("status_type", oracledbtype.varchar2, status_type, parameterdirection.input));      string connstr = configurationmanager.connectionstrings["tgsdatabaseconnection"].connectionstring;     using (oracleconnection dbconn = new oracleconnection(connstr))     {         dataset userdataset = new dataset();         var strquery = "select * lims_sample_results_vw room = :room , dob > :dob_gt , dob < :dob_lt , status_type= :status_type ";          var returnobject = new { data = new oracledatatablejsonresponse(connstr, strquery, prms.toarray()) };         var response = request.createresponse(httpstatuscode.ok, returnobject, mediatypeheadervalue.parse("application/json"));         contentdispositionheadervalue contentdisposition = null;         if (contentdispositionheadervalue.tryparse("inline; filename=tgsdata.json", out contentdisposition))         {             response.content.headers.contentdisposition = contentdisposition;         }         return response;     } 

with code above return room cannot empty or null how "error":"room cannot empty or null". there way handle error in urli , return json response "error":"poorly formed uri"

you can build anonymous type error(s) want return.

if (string.isnullorempty(room))     {         return this.request.createresponse(         httpstatuscode.badrequest,         new { error= "room cannot empty or null" });         resp.content.headers.contenttype =             new mediatypeheadervalue("application/json");         return resp;     }