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');
    }
}

在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

问题已经解决了，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

我发现你的代码对了解如何提取事件的信息非常有帮助，但我遇到了一个问题。我把它写在这里，以防它能帮助任何人。

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

在一些digging之后，它似乎是Web3py的一个限制，并且可以用之前的事件实例化来修复。因此，代码应该是：

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)