local_filter_middleware doesn't work with geth nodes

[tsudmi]

Hi,

get_filter_changes() raises exception when used with local_filter_middleware.

Traceback (most recent call last):
  File "/pyroot/lib/python3.7/site-packages/web3/_utils/filters.py", line 121, in get_new_entries
    log_entries = self._filter_valid_entries(self.web3.eth.getFilterChanges(self.filter_id))
  File "/pyroot/lib/python3.7/site-packages/web3/eth.py", line 402, in getFilterChanges
    "eth_getFilterChanges", [filter_id],
  File "/pyroot/lib/python3.7/site-packages/web3/manager.py", line 109, in request_blocking
    response = self._make_request(method, params)
  File "/pyroot/lib/python3.7/site-packages/web3/manager.py", line 96, in _make_request
    return request_func(method, params)
  File "/pyroot/lib/python3.7/site-packages/web3/middleware/filter.py", line 313, in middleware
    return {'result': next(_filter.filter_changes)}
StopIteration

• Version: 5.3.0
• Python: 3.7
• OS: linux
• Node type: geth
• Node version: 1.9.7-stable

[kclowes]

@tsudmi will you provide a minimum reproducible example please? That will help troubleshoot exactly what is going on. Thanks!

[tsudmi]

Hi @kclowes ,

I run something like this:

from web3 import Web3
from web3.middleware import geth_poa_middleware, local_filter_middleware

WEB3_WS_ENDPOINT = ''
CONTRACT_ADDRESS = ''
ABI = []

w3 = Web3(Web3.WebsocketProvider(WEB3_WS_ENDPOINT))
w3.middleware_onion.add(local_filter_middleware)

contract = w3.eth.contract(
    abi=ABI,
    address=CONTRACT_ADDRESS
)
event_filter = contract.events.SomeEvent.createFilter(fromBlock=w3.eth.blockNumber)
events = event_filter.get_new_entries()

The error occures quite randomly, but regularly.

[pipermerriam]

@kclowes it looks a lot like that StopIteration just needs to be caught and handled. Without having looked at the code I suspect it will mean "no new logs" but I'm not confident in that diagnosis.