Error using webread and websave to retrieve JSON data from RESTful web service

version '9.7.0.1247435 (R2019b) Update 2'

I am attempting to read data returned from a web service using either webread or websave. The relevant MATLAB code is as follows:

service_url = "https://webservice.testserver.com/results?format=json";
opts = weboptions("HeaderFields", {'Authorization' api_token});
results_resp = webread(service_url, opts);

The error returned is:

Error using matlab.internal.webservices.HTTPConnector/copyContentToFile (line 412)

The server returned the status 400 with message "Bad Request" in response to the request to URL

https://webservice-redirect.testserver.com/output.json

Error in readContentFromWebService (line 62)

copyContentToFile(connection, filename);

Error in webread (line 125)

[varargout{1:nargout}] = readContentFromWebService(connection, options);

I have also tried websave, with the code above becoming:

service_url = "https://webservice.testserver.com/results?format=json";
opts = weboptions("HeaderFields", {'Authorization' api_token});
results_resp = websave("the_json_file.txt", service_url, opts);

The error returned is similar:

Error using matlab.internal.webservices.HTTPConnector/copyContentToFile (line 412)

The server returned the status 400 with message "Bad Request" in response to the request to URL

https://webservice-redirect.testserver.com/output.json

Error in websave (line 107)

copyContentToFile(connection, filename);

I note that the following command using curl on the Linux command line works fine.

curl -H "Authorization: api_token" -L "https://webservice.testserver.com?format=json"

Answer 1

[Tim Kennedy]

As a workaround, I was able to solve this by using the Python requests module - calling this from MATLAB using the following:

service_url = "https://webservice.testserver.com/results";
import py.requests.get
headers = py.dict(pyargs('Authorization', api_token));
params = py.tuple({'format', 'json'});
results_resp = get(service_url, pyargs('headers', headers, 'params', params));
json_data = jsondecode(native2unicode(results_resp.content));

The last line converts the Python returned response results_resp.content into a MATLAB struct, for the JSON data returned in my case, for parsing.