websocket深堀り4回シリーズ-2 関数型をクラス型に書き換えてみた

#pip install websocket-client
import websocket
import json
from pprint import pprint
#import pandas as pd
CHANNEL = "lightning_executions_BTC_JPY"

def on_message(ws, message):
    message = json.loads(message)
    pprint(message)

def on_open(ws):
    ws.send(json.dumps({"method": "subscribe",
                        "params": {"channel": CHANNEL}}))

if __name__ == "__main__":
    ws = websocket.WebSocketApp("wss://ws.lightstream.bitflyer.com/json-rpc",
                                on_message=on_message, on_open=on_open)
    ws.run_forever()


データ内容を理解するため、データ丸ごと表示してみる。
ここから必要なものを辞書のキーを指定して取り出す
{'jsonrpc': '2.0',
 'method': 'channelMessage',
 'params': {'channel': 'lightning_executions_BTC_JPY',
            'message': [{'buy_child_order_acceptance_id': 'JRF20210516-210717-231265',
                         'exec_date': '2021-05-16T21:07:17.4793855Z',
                         'id': 2213681509,
                         'price': 4884761.0,
                         'sell_child_order_acceptance_id': 'JRF20210516-210717-314050',
                         'side': 'SELL',
                         'size': 0.0138},
                        {'buy_child_order_acceptance_id': 'JRF20210516-210702-341601',
                         'exec_date': '2021-05-16T21:07:17.4793855Z',
                         'id': 2213681510,
                         'price': 4884760.0,
                         'sell_child_order_acceptance_id': 'JRF20210516-210717-314050',
                         'side': 'SELL',
                         'size': 0.25145526}]}}
例えば、レスポンス['Params']['message'][0]['price']とすれば価格が抽出できる

class BfWebSocket():
    def __init__(self):
        self.CHANNEL = "lightning_executions_BTC_JPY"
        self.url = "wss://ws.lightstream.bitflyer.com/json-rpc"

    def run(self):
        # note: reconnection handling needed.
        ws = websocket.WebSocketApp(self.url,  on_message=self.on_message, on_open=self.on_open)
        ws.run_forever()

    def on_message(self,ws, message):
        self.message = json.loads(message)
        #目的のデータを抽出する
        if self.message["method"] == "channelMessage":
            self.last1=self.message["params"]["message"][0]
            print(f'\nBitfler_BTC {self.last1["exec_date"][:19]} {int(self.last1["price"]):,.0f} {self.last1["side"]:4} {self.last1["size"]:.2f}\n')

    def on_open(self,ws):
        ws.send(json.dumps({"method": "subscribe",
                            "params": {"channel": self.CHANNEL}}))
stream=BfWebsocket()
stream.run_forever()

出力
BF_BTC 2021-05-18T10:50:27 4,936,442 SELL 0.01
BF_BTC 2021-05-18T10:50:34 4,937,563 BUY  0.01