如何通过Web3利用交易哈希获取交易中的代币兑换数量？

你用web3.eth.get_transaction()拿到的只是交易基础数据，要获取实际兑换的代币数量，有两种可靠方法：

方式一：解码交易的input数据 #

交易的input字段包含了调用合约函数的参数，PancakeSwap Router的Swap函数参数里包含了用户输入的代币数量（最小输出量是预期值，实际量要从日志取）。可以用web3的解码工具解析：

from web3 import Web3

bsc = 'https://bsc-dataseed.binance.org/'
web3 = Web3(Web3.HTTPProvider(bsc))

tx_hash = "0x77c5949df82ce8625d9e578fc696bc7264c99dbea4f763ce1fcdbe59dac5f029"
tx = web3.eth.get_transaction(tx_hash)

# 对应PancakeSwap Router V2的swapExactTokensForTokensSupportingFeeOnTransferTokens函数ABI片段
swap_abi = [{
    "inputs": [
        {"internalType": "uint256", "name": "amountIn", "type": "uint256"},
        {"internalType": "uint256", "name": "amountOutMin", "type": "uint256"},
        {"internalType": "address[]", "name": "path", "type": "address[]"},
        {"internalType": "address", "name": "to", "type": "address"},
        {"internalType": "uint256", "name": "deadline", "type": "uint256"}
    ],
    "name": "swapExactTokensForTokensSupportingFeeOnTransferTokens",
    "outputs": [],
    "stateMutability": "nonpayable",
    "type": "function"
}]

# 解码input数据
function_obj, params = web3.eth.decode_function_input(tx.input)

# 输入的BUSD数量（BUSD是18位小数）
amount_in = params['amountIn'] / 10**18
print(f"输入BUSD数量: {amount_in}")
print(f"兑换路径代币地址: {params['path']}")

方式二：解析交易收据日志（获取实际兑换量） #

amountOutMin只是用户设置的最低接收量，实际到账的代币数量要从交易触发的Transfer事件日志提取：

# 获取交易收据
tx_receipt = web3.eth.get_transaction_receipt(tx_hash)

# ERC20标准Transfer事件ABI
transfer_event_abi = {
    "anonymous": False,
    "inputs": [
        {"indexed": True, "internalType": "address", "name": "from", "type": "address"},
        {"indexed": True, "internalType": "address", "name": "to", "type": "address"},
        {"indexed": False, "internalType": "uint256", "name": "value", "type": "uint256"}
    ],
    "name": "Transfer",
    "type": "event"
}

# 目标Shitcoin代币地址
target_token = "0x31b35fdaa0780a75dd08a1a631c03e34fcef7173"
transfer_topic = web3.eth.event_abi_to_log_topic(transfer_event_abi)

# 遍历日志提取Transfer事件
for log in tx_receipt['logs']:
    if log['address'].lower() == target_token.lower() and log['topics'][0] == transfer_topic:
        decoded_log = web3.eth.decode_logs([transfer_event_abi], log)[0]
        # 代币小数位数需对应合约的decimals()方法，这里假设是18位
        actual_amount_out = decoded_log['args']['value'] / 10**18
        print(f"实际获得Shitcoin数量: {actual_amount_out}")

补充说明 #

• 你的交易调用的是支持手续费代币的Swap函数（签名0x5c11d795），这类函数不会在参数里返回实际输出量，必须从Transfer日志提取。
• 代币小数位数不要硬编码，最好调用代币合约的decimals()方法获取准确值。

内容的提问来源于stack exchange，提问作者Soma Juice