error creating filter for event with array arguments

[KaiRo-at]

• Version: 5.4.0
• Python: 3.7
• OS: linux
• pip freeze output

asn1crypto==1.3.0
attrdict==2.0.1
attrs==19.3.0
base58==1.0.3
blinker==1.4
certifi==2019.11.28
cffi==1.13.2
chardet==3.0.4
Click==7.0
coincurve==13.0.0
cryptography==2.8
cytoolz==0.10.1
eciespy==0.3.3
eth-abi==2.1.0
eth-account==0.4.0
eth-hash==0.2.0
eth-keyfile==0.5.1
eth-keys==0.3.1
eth-rlp==0.1.2
eth-typing==2.2.1
eth-utils==1.8.4
flasgger==0.9.3
Flask==1.1.1
Flask-Cors==3.0.8
Flask-Mail==0.9.1
gevent==1.4.0
greenlet==0.4.15
hexbytes==0.2.0
idna==2.8
importlib-metadata==1.3.0
ipfshttpclient==0.4.12
itsdangerous==1.1.0
Jinja2==2.10.3
jsonschema==3.2.0
lru-dict==1.1.6
MarkupSafe==1.1.1
mistune==0.8.4
more-itertools==8.0.2
multiaddr==0.0.9
mypy-extensions==0.4.3
netaddr==0.7.19
parsimonious==0.8.1
protobuf==3.11.2
psycopg2==2.8.4
pycparser==2.19
pycryptodome==3.9.4
pyrsistent==0.15.7
PyYAML==5.3
requests==2.22.0
rlp==1.2.0
six==1.13.0
SQLAlchemy==1.3.12
SQLAlchemy-Utils==0.36.1
toolz==0.10.0
typing-extensions==3.7.4.1
urllib3==1.25.7
varint==1.0.2
web3==5.4.0
websockets==8.1
Werkzeug==0.16.0
zipp==0.6.0

What was wrong?

I'm trying to set up event filters for ERC 1155 transfer events (see https://eips.ethereum.org/EIPS/eip-1155#specification for the spec) with code like this (simplified):

    for ev in ["TransferSingle", "TransferBatch"]:
        contract = w3.eth.contract(address=mycontract_address, abi=mycontract_abi)
        # the below should work but for some reason does not:
        #event_filter = contract.events.__getattr__(ev).createFilter(fromBlock=mycontract_deployblock, toBlock="latest")
        event_filter = None
        for cevent in contract.events:
            if cevent.event_name == ev:
                event_filter = cevent.createFilter(fromBlock=mycontract_deployblock, toBlock="latest")
                break

This works for TransferSingle, but for TransferBatch it fails like this:

Traceback (most recent call last):
  File "./mycode-rest.py", line 2080, in check_background_threads
    event_filter = cevent.createFilter(fromBlock=mycontract_deployblock, toBlock="latest")
  File "/mnt/dev/project/rest-backend/venv/lib/python3.7/site-packages/eth_utils/decorators.py", line 20, in _wrapper
    return self.method(objtype, *args, **kwargs)
  File "/mnt/dev/project/rest-backend/venv/lib/python3.7/site-packages/web3/contract.py", line 1158, in createFilter
    log_filter = filter_builder.deploy(self.web3)
  File "/mnt/dev/project/rest-backend/venv/lib/python3.7/site-packages/web3/_utils/events.py", line 397, in deploy
    for arg in self.args.values():
TypeError: 'DataArgumentFilter' object is not callable

Now, TransferBatch is specified like this:
event TransferBatch(address indexed _operator, address indexed _from, address indexed _to, uint256[] _ids, uint256[] _values);

Note the arrays for _ids and _values - I suspect that's what causes the error, as the same code has worked fine for me for all kinds of events so far, but none had arrays in it before this one.

How can it be fixed?

Not sure, I know too little of handling events in the guts of web3.py to speculate on that.

[KaiRo-at]

I have worked around this for the moment with a generic web3.eth.filter() on the topic, which I read out of the contract's .json file and then dedode the arguments from the event's data field via eth_abi.decode_single() but this is pretty cumbersome code when it should be supported straight-forward by web3.py instead.

[kclowes]

Thanks for posting an update @KaiRo-at. I'm glad you were able to figure out a workaround. I'll leave this open so we can dig in.

[kclowes]

This should be working with the latest versions of web3 and eth-abi. Tuple support has been added.