Handle json error message from REST API through HTTPWebRepsonse - asp.net

Question

I am consuming REST API (provided by client) in C#/asp.net and manipulate json result returned by that REST API. i have consume it by following code.
HttpWebResponse res = null;
string ReturnBody = string.Empty;
string requestBody = string.Empty;
WebRequest request = WebRequest.Create(Path);
request.ContentType = "application/json";
request.Method = "POST";
request.ContentLength = json.Length;
//Add Basic Auhtentication header
string authInfo = Username + ":" + Password;
authInfo = Convert.ToBase64String(Encoding.Default.GetBytes(authInfo));
request.Headers["Authorization"] = "Basic " + authInfo;
System.IO.StreamWriter sw = new System.IO.StreamWriter(request.GetRequestStream());
sw.Write(json);
sw.Close();
res = (HttpWebResponse)request.GetResponse();
if (res != null)
{
using (StreamReader sr = new StreamReader(res.GetResponseStream(), true))
{
ReturnBody = sr.ReadToEnd();
StringBuilder s = new StringBuilder();
s.Append(ReturnBody);
sr.Close();
}
}
I have put above code in try catch block, so it works properly if it will return success code(200) so i can consume json response from res object as per above code
but when that REST API gives error then it will redirect to catch and res will be null so i can not access json response of error message as i can get it by Fiddler as per shown in below fig.
so help me about How can i consume that json error response through my code?
Thanks in Advance! for any help.

Answer 1

You will be probably getting WebException - inspect the status property. In your case, it will indicate protocol error i.e. 401/403 etc. In such case Response property can be use to get actual HTTP response. For example,
try
{
res = (HttpWebResponse)request.GetResponse();
// handle successful response
...
}
catch(WebException ex)
{
if (ex.Status == WebExceptionStatus.ProtocolError)
{
var response = (HttpWebResponse)ex.Response;
// use the response as needed - in your case response.StatusCode would be 403
// and body will have JSON describing the error.
..
}
else
{
// handle other errors, perhaps re-throw
throw;
}
}