如何从 web3py 获取事件数据？

Question

pragma solidity ^0.4.17

contract Test {
    event greeting(string name);
    function say() pure public {
        greeting('jack');
    }
}

python版本web3.py中调用say()函数时如何获取事件数据“jack”？ 下面是我的python代码。

contractAddress = '0x345ca3e014aaf5dca488057592ee47305d9b3e10'
contract = w3.eth.contract(address=contractAddress, abi=abiJson['abi'])
accounts = w3.eth.accounts

def handle_event(event):
    print(event)

def log_loop(event_filter, poll_interval):
    while True:
        for event in event_filter.get_new_entries():
            handle_event(event)
            time.sleep(poll_interval)

block_filter = w3.eth.filter({'fromBlock':'latest', 'address':contractAddress})
log_loop(block_filter, 2)

Answer 1

问题已经解决，正确的代码应该如下所示：

contractAddress = '0x345ca3e014aaf5dca488057592ee47305d9b3e10'
contract = w3.eth.contract(address=contractAddress, abi=abiJson['abi'])
accounts = w3.eth.accounts

def handle_event(event):
    receipt = w3.eth.waitForTransactionReceipt(event['transactionHash'])
    result = contract.events.greeting.processReceipt(receipt)
    print(result[0]['args'])

def log_loop(event_filter, poll_interval):
    while True:
        for event in event_filter.get_new_entries():
            handle_event(event)
            time.sleep(poll_interval)

block_filter = w3.eth.filter({'fromBlock':'latest', 'address':contractAddress})
log_loop(block_filter, 2)

Answer 2

我发现您的代码对于了解如何提取事件信息非常有帮助，但我遇到了一个问题。 我会把它写在这里以防万一它可以帮助任何人。

行result = contract.events.greeting.processReceipt(receipt)抛出错误： _parse_logs() missing 1 required positional argument: 'errors'

经过一番挖掘，它似乎是 Web3py 的一个限制，它可以通过事件的先前实例化来修复。 所以，代码将是：

contractAddress = '0x345ca3e014aaf5dca488057592ee47305d9b3e10'
contract = w3.eth.contract(address=contractAddress, abi=abiJson['abi'])
accounts = w3.eth.accounts
greeting_Event = contract.events.greeting() # Modification

def handle_event(event):
    receipt = w3.eth.waitForTransactionReceipt(event['transactionHash'])
    result = greeting_Event.processReceipt(receipt) # Modification
    print(result[0]['args'])

def log_loop(event_filter, poll_interval):
    while True:
        for event in event_filter.get_new_entries():
            handle_event(event)
            time.sleep(poll_interval)

block_filter = w3.eth.filter({'fromBlock':'latest', 'address':contractAddress})
log_loop(block_filter, 2)