eth-event
Tools for Ethereum event decoding and topic generation.
Installation
You can install the latest release via pip:
pip install eth-eventOr clone the repository and use setuptools for the most up-to-date version:
git clone https://github.com/iamdefinitelyahuman/eth-event.git
cd eth-event
python3 setup.py installUsage
The public API is well documented within the docstrings. The following example may also help:
>>> from eth_event import get_topics
# generating a topic map
>>> abi = open('abi.json').read()
>>> topic_map = get_topic_map(abi)
>>> topic_map
{
'0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef': {
'name': 'Transfer',
'inputs': [
{'name': 'from', 'type': 'address', 'indexed': True},
{'name': 'to', 'type': 'address', 'indexed': True},
{'name': 'value', 'type': 'uint256', 'indexed': False}
]
}
}
# decoding event logs from a transaction receipt
>>> tx = token.transfer(account[1], 100, {'from': account[0]})
<Transaction object '0x615a157e84715d5f960a38fe2a3ddb566c8393cfc71f15b06170a0eff74dfdde'>
>>> eth_event.decode_logs(tx.logs, topic_map)
[{
'name': 'Transfer',
'address': "0x3194cBDC3dbcd3E11a07892e7bA5c3394048Cc87",
'data': [
{'name': 'from', 'type': 'address', 'value': '0xbd4940951bfa463f8fb6db762e55686f6cfdb73a', 'decoded': True},
{'name': 'to', 'type': 'address', 'value': '0xbd4940951bfa463f8fb6db762e55686f6cfdb73a', 'decoded': True},
{'name': 'tokens', 'type': 'uint256', 'value': 100, 'decoded': True}
],
}]
# decoding a structLog from Geth's debug_traceTransaction endpoint
>>> trace = web3.provider.make_request(
"debug_traceTransaction",
['0x615a157e84715d5f960a38fe2a3ddb566c8393cfc71f15b06170a0eff74dfdde', {}]
)
>>> struct_log = trace['result']['structLogs']
>>> eth_event.decode_trace(struct_log, topic_map, initial_address="0x3194cBDC3dbcd3E11a07892e7bA5c3394048Cc87")
[{
'name': 'Transfer',
'address': "0x3194cBDC3dbcd3E11a07892e7bA5c3394048Cc87",
'data': [
{'name': 'from', 'type': 'address', 'value': '0xbd4940951bfa463f8fb6db762e55686f6cfdb73a', 'decoded': True},
{'name': 'to', 'type': 'address', 'value': '0xbd4940951bfa463f8fb6db762e55686f6cfdb73a', 'decoded': True},
{'name': 'tokens', 'type': 'uint256', 'value': 100, 'decoded': True}
],
}]Limitations
-
If an array is indexed in an event, the topic is generated as a sha3 hash and so cannot be decrypted. In this case, the unencrypted topic is returned and
decodedis set toFalse. -
Anonymous events cannot be decoded. Use the
allow_undecodedkwarg when callingdecode_logsanddecode_traceto receive the undecoded log without raising an exception. -
When decoding a trace, the initial address for the call cannot be determined. To include addresses where decoded events were emitted you must supply the initial address with the
initial_addresskeyword argument.
Tests
To run the test suite:
$ toxDevelopment
This project is still in development. Comments, questions, criticisms and pull requests are welcomed.
License
This project is licensed under the MIT license.