如何引用 websocket 数据数组 python-binance

Question

I have a script that receives this binance json data array via websocket and prints to console via callback function:

{"e":"outboundAccountPosition","E":1600502318390,"u":1600502318389,"B":[{"a":"BTC","f":"0.00000000","l":"0.00000000"},{"a":"BNB","f":"0.00000000","l":"0.00000000"},{"a":"XTZ","f":"0.00000000","l":"0.00000000"}]}

I need to be able to reference the BNB balance ["B"]["f"] in the callback function. I have tried code like this but does not work.

def callback_function(msg)
    if msg['e'] == 'outboundAccountPosition':
    print(msg["B"]["f"])

Printing the whole message works fine so I figured I was referencing the data array wrong. How to fix? Thanks

Answer 1

You just received a string that contains a JSON structure. Its possible to convert this to a python dict.

You can use every JSON lib for that, the fastest is ujson:

import ujson as json

stream_data_dict = json.loads(stream_data_json)
print(stream_data_dict["B"]["f"])

A library that does this for you and forms well named dicts is unicorn_fy: https://github.com/oliver-zehentleitner/unicorn_fy

from unicorn_fy.unicorn_fy import UnicornFy

received_stream_data_json = {"stream": "btcusdt@trade",
                             "data": {"e": "trade",
                                      "E": 1556876873656,
                                      "s": "BTCUSDT",
                                      "t": 117727701,
                                      "p": "5786.76000000",
                                      "q": "0.03200500",
                                      "b": 341831847,
                                      "a": 341831876,
                                      "T": 1556876873648,
                                      "m": True,
                                      "M": True}}

unicorn_fied_stream_data = UnicornFy.binance_com_websocket(received_stream_data_json)
print(unicorn_fied_stream_data)
>>>
{'stream_type': 'btcusdt@trade', 'event_type': 'trade', 'event_time': 1556876873656, 'symbol': 'BTCUSDT', 'trade_id': 117727701, 'price': '5786.76000000', 'quantity': '0.03200500', 'buyer_order_id': 341831847, 'seller_order_id': 341831876, 'trade_time': 1556876873648, 'is_market_maker': True, 'ignore': True, 'unicorn_fied': ['binance', '0.1.0']}