trouble with the low-level backtest tutorial

[ViN807]

I'm working through the low-level backtest tutorial and I'm having trouble with configuring the strategy, particularly the bar_type declaration. I think 'from nautilus_trader.model.data import BarType' should be included with the other import statements, but even when adding this I get the following error:

    bar_type=BarType("ETHUSDT.BINANCE-250-TICK-LAST-INTERNAL"),
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "nautilus_trader\\model\\data.pyx", line 639, in nautilus_trader.model.data.BarType.__init__
TypeError: __init__() takes at least 2 positional arguments (1 given)

I can't determine if the issue is with parsing the argument to BarType or if its something else. Any help is appreciated.

[OnlyC]

You should use BarType.from_str("ETHUSDT.BINANCE-250-TICK-LAST-INTERNAL")

[cjdsellers]

Hi @ViN807

Thanks for helped there @OnlyC.

I also checked the entire codebase and thankfully we don't try to pass a string to the constructor anywhere else. You need to use the from_str method as OnlyC points out.