Python Poloniex API Call

Question

I have the following code that I am trying to make an API call to Poloniex according to their instructions

import urllib
import urllib.request
import json
import time
import hashlib
import codecs
import hmac 
import time


Key = "whatever your key is"
Sign = "whatever your secret is"

def returnBalances(balances):
    nonce = int(round(time.time()-599900000)*10)
    parms = {"returnBalances":balances,
             "nonce":nonce}

    parms = urllib.parse.urlencode(parms)
    hashed = hmac.new(b'Sign',digestmod=hashlib.sha512)
    signature = hashed.hexdigest()

    headers = {"Content-type":"application/x-www-form-urlencoded",
               "Key":Key,
               "Sign":signature}

    conn = urllib.request.urlopen("https://poloniex.com")
    conn.request("POST","/tradingApi",parms,headers)

    response = conn.getresponse()
    print(response.status,response.reason)

returnBalances('balances')

When I run this I get this error message

HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 403: Forbidden

Can someone please help?

t.m.adam · Accepted Answer · 2017-12-24T11:56:15.390

2

You can catch HTTP errors with urllib.error.HTTPError
POST data should be bytes, so you have to encode parms
urllib.request.urlopen returns a HTTPResponse object, which has no request method.
If you want to set headers and other parameters you should use urllib.request.Request
According to the api docs the post parameters should be 'nonce' and 'command', so i modified your function to accept 'returnBalances' as a parameter and use it in parms["command"]

def api_call(command):
    nonce = int(round(time.time()-599900000)*10)
    parms = {"command":command, "nonce":nonce}
    parms = urllib.parse.urlencode(parms).encode()

    hashed = hmac.new(Sign.encode(), parms, digestmod=hashlib.sha512)
    signature = hashed.hexdigest()
    headers = {"Key":Key, "Sign":signature}

    req = urllib.request.Request("https://poloniex.com/tradingApi", headers=headers)
    try:
        conn = urllib.request.urlopen(req, data=parms)
    except urllib.error.HTTPError as e:
        conn = e
    print(conn.status,conn.reason)
    return json.loads(conn.read().decode())

balances = api_call("returnBalances")

edited Dec 24 '17 at 11:56

answered Dec 24 '17 at 09:15

t.m.adam

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That's really nice looking code man thanks so much for clearing that up, very helpful. When I run the script however I still seem to be getting "TypeError: the JSON object must be str, not 'bytes'" I am assuming this has to be converted to a byte stream and if so how might one do that? – Jo3Dirt Dec 24 '17 at 11:10
That's strange, [json.loads](https://docs.python.org/3/library/json.html#json.loads) accepts string or bytes (assuming that the exception was raised by `json.loads(conn.read())`). Still, you can decode the response to string, see updated code – t.m.adam Dec 24 '17 at 11:21
OK, that fixed it thank you! No errors this time but 403 Forbidden :-( – Jo3Dirt Dec 24 '17 at 11:36
What do you get with `print(balances)`? – t.m.adam Dec 24 '17 at 11:41
Oh right..I get "{'error': 'Invalid API key/secret pair.'}" I am assuming I need to generate a new one? – Jo3Dirt Dec 24 '17 at 11:45
No, wait. In `hmac.new` you pass `'Sign'` (string not value) as key. Also you don't update with `parms`. Updated my answer, try again. – t.m.adam Dec 24 '17 at 12:02
Perfect mate! Your a champ!! – Jo3Dirt Dec 24 '17 at 12:03
Very glad i could help! – t.m.adam Dec 24 '17 at 12:08

Python Poloniex API Call

1 Answers1