Extending a Datafeed

[蔡昇剛]

I'm trying to add extending data to my data feed, but when I output, It showed " AttributeError: 'Lines_LineSeries_DataSeries_OHLC_OHLCDateTime_Abst' object has no attribute 'longshort_ratio' " I have readExtending a Datafeed, How to Feed Backtrader Alternative Data
, and still don't know what went wrong.

Here is my code:

import datetime

import backtrader as bt
import pandas as pd


class ExtraPandasDirectData(bt.feeds.PandasDirectData):
    lines = ('longshort_ratio', )
    params = (('longshort_ratio', -1), )

    datafields = bt.feeds.PandasData.datafields + (['longshort_ratio'])


class MyStrategy(bt.Strategy):

    def __init__(self):
        print(*self.data.longshort_ratio)


cerebro = bt.Cerebro()

Kline = pd.read_csv('Data/data.csv')
Kline['datetime'] = pd.to_datetime(Kline['datetime'])
Kline.set_index('datetime', inplace=True)
feed = bt.feeds.PandasDirectData(
    dataname=Kline,
    fromdate=datetime.datetime(2022, 3, 11, 0, 0, 0),
    todate=datetime.datetime(2022, 4, 10, 15, 0, 0),
    timeframe=bt.TimeFrame.Minutes,
    compression=60)

cerebro.adddata(feed)

cerebro.addstrategy(MyStrategy)

cerebro.run()

The output message:

Here is my data:

Thanks in advance!