c# - Return Different JSON in WCF method on error -

i have method return class cono in json format

  [datacontract] public class cono {     [datamember(order = 1)]     public companies[] companies;  } public class companies {     [datamember(order = 1)]     public string cono;     [datamember(order = 2)]     public string name; }        [webget(uritemplate = "getcompanies?requestkey={requestkey}", responseformat = webmessageformat.json)]         public cono getcompanies(string requestkey); 

this method first validate request key if correct returns data this:

{ companies: [ { cono: "001", name: "company001" } ] } 

but if request key not correct want return error code in json this

{-100} 

how can change return type of method int or how can return desired data in above format

you can change return type of method stream (public stream getcompanies(string requestkey);) , write method

static stream tojson(object o) {     var result = jsonconvert.serializeobject(o);     var data = encoding.utf8.getbytes(result);      weboperationcontext.current.outgoingresponse.contenttype = "application/json; charset=utf-8";     weboperationcontext.current.outgoingresponse.contentlength = data.length;     return new memorystream(data); } 

then, in method, can use

........ return tojson(anyobject)