How do I look at the payload of a webwrite response when the response is a 400 or other error?

How do I look at the payload of a "webwrite" response when the response is a 400 or other error? It throws a MATLAB error, but doesn't display any of the error messages the server sent back as payload.

My code looks something like this:

json_request = struct('a', nan);
json_response = webwrite('http://localhost:8000/reports/', json_request, ...
    weboptions('MediaType', 'application/json', 'RequestMethod', 'post'))

Answer 1

[MathWorks Support Team]

So basically, you can't get the payload of an error response using "webwrite". However you can get this using the HTTP interface. It might look something like:

import matlab.net.http.*
r = RequestMessage;
resp = r.send(url); %replace url with your target address
show(resp)

Answer 2

[Richard Zapor]

A slight variation on the Accepted answer is for when Posting a JSON string.

import matlab.net.http.*
body = MessageBody(jsonencode(data)); % or body=data_string of JSON
r = RequestMessage('POST', [], body); 
resp = r.send(url);
show(resp)
resp.Body.Data  %To see the error message content