btc38-test.py

import requests
import pprint

pp = pprint.PrettyPrinter(indent=4)
feed  = {}
url = "http://api.btc38.com/v1/ticker.php"
scaleVolumeBy = 10
quotes=["BTC","BTS"]
bases=["BTC", "CNY","BTS"]

_request_headers = {'content-type': 'application/json',
                    'User-Agent': 'Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:22.0) Gecko/20100101 Firefox/22.0'}

for base in bases :
  try:
      feed[base] = {}
      for quote in quotes :
          if base == quote :
              continue

          params = {'c': quote.lower(), 'mk_type': base.lower()}
          print("Checking quote (params[c]) = "+ quote.lower() + " base (params[mk_type]) = " +  base.lower() + " / url = http://api.btc38.com/v1/ticker.php?c="+quote.lower()+"&mk_type="+base.lower());

          response = requests.get(url=url, params=params, headers=_request_headers, timeout=20)
          print(response.content)
          result = response.json()
          #print(result)
          feed["response"] = result
          if "ticker" in result and \
             "last" in result["ticker"] and \
             "vol" in result["ticker"] :
              feed[base][quote] = {"price"  : (float(result["ticker"]["last"])),
                                   "volume" : (float(result["ticker"]["vol"]) * scaleVolumeBy)}
          else :
              print("\nFetched data from {0} is empty!".format(type(self).__name__))
              continue
  except Exception as e:
      print("\nError fetching results from {1}! ({0})".format(str(e), 'btc38 script'))
      pass

pp.pprint(feed)

I swapped the try - except block from outside the for loop to inside the for loop to continue on errors. Notice the first pairs
BTC/BTS hits on an non-json error from BTC38 APY. I think that is also the case with the new bitshares-pricefeed ?

Here is the output of the above script:

Checking quote (params[c]) = bts base (params[mk_type]) = btc / url = http://api.btc38.com/v1/ticker.php?c=bts&mk_type=btc
b'fail#2'

Error fetching results from btc38 script! (Expecting value: line 1 column 1 (char 0))
Checking quote (params[c]) = btc base (params[mk_type]) = cny / url = http://api.btc38.com/v1/ticker.php?c=btc&mk_type=cny
b'{"ticker":{"high":8340,"low":8126,"last":8249,"vol":190.763347,"buy":8223,"sell":8249}}'
Checking quote (params[c]) = bts base (params[mk_type]) = cny / url = http://api.btc38.com/v1/ticker.php?c=bts&mk_type=cny
b'{"ticker":{"high":0.0942,"low":0.077,"last":0.0859,"vol":54243118.916969,"buy":0.086,"sell":0.0867}}'
Checking quote (params[c]) = btc base (params[mk_type]) = bts / url = http://api.btc38.com/v1/ticker.php?c=btc&mk_type=bts
b'{"ticker":{"high":8340,"low":8126,"last":8249,"vol":190.763347,"buy":8223,"sell":8249}}'
{   'BTC': {},
    'BTS': {'BTC': {'price': 8249.0, 'volume': 1907.6334700000002}},
    'CNY': {   'BTC': {'price': 8249.0, 'volume': 1907.6334700000002},
               'BTS': {'price': 0.0859, 'volume': 542431189.16969}},
    'response': {   'ticker': {   'buy': 8223,
                                  'high': 8340,
                                  'last': 8249,
                                  'low': 8126,
                                  'sell': 8249,
                                  'vol': 190.763347}}}```

Good point .. it breaks the loop if only one of the quote or base assets break .. ignoring everything that comes later on ..
Maybe i should rework the whole section. The point of the Exceptions is so that I can break the whole script if I miss a significant exchange as defined in the config. Ideally, i don't need to deal with exchanges providing non-json returns. Maybe I should add some checks for HTTP error codes ..