DataCls does autoregister

Kevin Galkov

Hi, Backtrader Community!

I am looking to use oandapyV20 instead of oandapy for the Oanda datastore that is in the codebase.
My account needs to use the new api, that's why.

I am confused about how the DataCls attribute [0] of the OandaStore is supposed to "auto" register?

If I run the mementum/backtrader/samples/oandatest/oandatest.py , it complains:

Traceback (most recent call last):
  File "/Users/kevin/pdev/tgkj/external/github/mementum/backtrader/samples/oandatest/oandatest.py", line 498, in <module>
    runstrategy()
  File "/Users/kevin/pdev/tgkj/external/github/mementum/backtrader/samples/oandatest/oandatest.py", line 310, in runstrategy
    cerebro.run(exactbars=args.exactbars)
  File "/usr/local/lib/python3.7/site-packages/backtrader/cerebro.py", line 1127, in run
    runstrat = self.runstrategies(iterstrat)
  File "/usr/local/lib/python3.7/site-packages/backtrader/cerebro.py", line 1264, in runstrategies
    strat._start()
  File "/usr/local/lib/python3.7/site-packages/backtrader/strategy.py", line 413, in _start
    self.start()
  File "/Users/kevin/pdev/tgkj/external/github/mementum/backtrader/samples/oandatest/oandatest.py", line 180, in start
    if self.data0.contractdetails is not None:
  File "/usr/local/lib/python3.7/site-packages/backtrader/lineseries.py", line 461, in __getattr__
    return getattr(self.lines, name)
AttributeError: 'Lines_LineSeries_DataSeries_OHLC_OHLCDateTime_Abst' object has no attribute 'contractdetails'

I think I might just want to specify: --no-store true , and then it will utilize OandaData?

Otherwise, what do we mean by auto register?

[0]
https://github.com/mementum/backtrader/blob/93ad8e2e2d3674e4b1bc0207cea265091747e737/backtrader/stores/oandastore.py#L193

vladisld

@Kevin-Galkov said in DataCls does autoregister:

I am confused about how the DataCls attribute [0] of the OandaStore is supposed to "auto" register?

I suppose the question is at which point the DataCls attribute of the OandaStore is initialized. This is happening during the instantiation of OandaData's metaclass (which by itself is happening during the chain of imports when the Backtrader module is imported into your code)

class MetaOandaData(DataBase.__class__):
    def __init__(cls, name, bases, dct):
        '''Class has already been created ... register'''
        # Initialize the class
        super(MetaOandaData, cls).__init__(name, bases, dct)

        # Register with the store
        oandastore.OandaStore.DataCls = cls

class OandaData(with_metaclass(MetaOandaData, DataBase)):
...

This is done in order to support two different usage scenarios:

The case where OandaData instance is instantiated directly, like:

data0 = OandaData(dataname=args.data0, **datakwargs)

The case where the OandaStore.getdata method is used for the same purpose:

data0 = bt.stores.OandaStore.getdata(dataname=args.data0, **datakwargs)

In case you need to use a different data class (like OandaV20), I'm afraid the new OandaStoreV2 should be introduced and initialized in a way similar to the original OandaStore. But probably there is another way and more experienced forum members may point it out.

backtrader

You have to use this:

https://github.com/ftomassetti/backtrader-oandav20

The built-in module is only compatible with the old Oanda API.

And oandatest.py works with the old built-in module.

backtrader

@Kevin-Galkov said in DataCls does autoregister:

If I run the mementum/backtrader/samples/oandatest/oandatest.py , it complains:

In any, it does complay because you don't have the proper package installed, you have something for v20.