Matlab urlread2 - HTTP response code: 415 for URL - matlab

Question

I am attempting to access the betfair API using Matlab and the urlread2 function available here.
EDIT: I have posted this problem on Freelancer if anyone can help with it: tinyurl.../pa7sblb
The documentation for the betfair API I am following is this getting started guide. I have successfully logged in and kept the session open using these codes: (I am getting a success response)
%% Login and get Token
url = 'https://identitysso.betfair.com/api/login';
params = {'username' '******' 'password' '******'};
header1 = http_createHeader('X-Application','*****');
header2 = http_createHeader('Accept','application/json');
header = [header1, header2];
[paramString] = http_paramsToString(params)
[login,extras] = urlread2(url,'POST',paramString,header)
login = loadjson(login)
token = login.token
%% Keep Alive
disp('Keep Session Alive')
url_alive = 'https://identitysso.betfair.com/api/keepAlive';
header1 = http_createHeader('X-Application','******');
header2 = http_createHeader('Accept','application/json');
header3 = http_createHeader('X-Authentication',token');
header_alive = [header1, header2, header3];
[keep_alive,extras] = urlread2(url_alive,'POST',[],header_alive);
keep_alive = loadjson(keep_alive);
keep_alive_status = keep_alive.status
My trouble starts when I am attempting to do the next step and load all available markets. I am trying to replicate this example code which is designed for Python
import requests
import json
endpoint = "https://api.betfair.com/exchange/betting/rest/v1.0/"
header = { 'X-Application' : 'APP_KEY_HERE', 'X-Authentication' : 'SESSION_TOKEN_HERE' ,'content-type' : 'application/json' }
json_req='{"filter":{ }}'
url = endpoint + "listEventTypes/"
response = requests.post(url, data=json_req, headers=header)
The code I am using for Matlab is below.
%% Get Markets
url = 'https://api.betfair.com/exchange/betting/rest/v1.0/listEventTypes/';
header_application = http_createHeader('X-Application','******');
header_authentication = http_createHeader('X-Authentication',token');
header_content = http_createHeader('content_type','application/json');
header_list = [header_application, header_authentication, header_content];
json_body = savejson('','filter: {}');
[list,extras] = urlread2(url_list,'POST',json_body,header_list)
I am having trouble with a http response code 415. I believe that the server cannot understand my parameter since the headings I have used with success previously.
Any help or advice would be greatly appreciated!
This is the error:
Response stream is undefined
below is a Java Error dump (truncated):
Error using urlread2 (line 217)
Java exception occurred:
java.io.IOException: Server returned HTTP response code: 415 for URL....

Answer 1

I looked at your problem and it seems to be caused by two things:
1) The content type should be expressed as 'content-type' and not 'content_type'
2) The savejson-function doesn't create an adequate json-string. If you use the json-request from the Python-script it works.
This code work for me:
%% Get Markets
url = 'https://api.betfair.com/exchange/betting/rest/v1.0/listEventTypes/';
header_application = http_createHeader('X-Application','*********');
header_authentication = http_createHeader('X-Authentication',token');
header_content = http_createHeader('content-type','application/json');
header_list = [header_application, header_authentication, header_content];
json_body = '{"filter":{ }}';
[list,extras] = urlread2(url,'POST',json_body,header_list)