比特币交易映射引发 KeyError答案

【问题标题】：Bitcoin Transaction Mapping Throws KeyError比特币交易映射引发 KeyError
【发布时间】：2020-07-16 08:19:53
【问题描述】：

我有以下一段代码，它似乎一直运行到第 36 行 recipientlist.append(target["addr"]) 然后抛出错误 KeyError: 'addr'

但是“地址”似乎在数据中，所以不确定是什么问题

有人可以帮忙吗？

import json
import requests

z = 0
i = 0
firstpart = "https://blockchain.info/rawaddr/"
initialinput = '3PaGEcGDjPsNQHAQ4pTmjQuLXWoEwvnr11'
initialreq = firstpart + initialinput

firstjson = (requests.get(initialreq)).json()
graphvizlines = []

addresslist = []
usedaddresslist = []

addresslist.append(initialinput)
usedaddresslist.append(initialinput)

while i < 6:
    if z is 1:
        initialreq = firstpart + addresslist[i]
        firstjson = (requests.get(initialreq)).json()
    
    for transaction in firstjson["txs"]:
        payerlist = []
        recipientlist = []
        
        print("\n" + transaction["hash"])

        for item in transaction["inputs"]:
            payerlist.append(item["prev_out"]["addr"])
            if item["prev_out"]["addr"] not in addresslist:
                addresslist.append(item["prev_out"]["addr"])

        for target in transaction["out"]:
            recipientlist.append(target["addr"])
            if target["addr"] not in addresslist:
                addresslist.append(target["addr"])

        for payer in payerlist:
            for recipient in recipientlist:
                a = '"' + payer + '"' + " -> " + '"' + recipient + '"' + ";"
                if a not in graphvizlines:
                    graphvizlines.append(a)
    i = i + 1    
    z = 1
        

for t in graphvizlines:
    print(t)

【问题讨论】：

标签： python python-3.x bitcoin

【解决方案1】：

虽然addr 存在于您的数据中，但它并非存在于每个inputs 元素中。检查txs 中的最后一个元素，您会看到inputs 是：

"inputs": [
    {
        "sequence": 0,
        "witness": "304402203f872bfd7093fcdad6a3735cbd76f276279890b0304e6f23f54c51388cc2a84402203731d7a7f71265f072f6792c8f4d2e805ff8f86bbfbd0b48a187d573c051593001",
        "prev_out": {
            "spent": true,
            "spending_outpoints": [
                {
                    "tx_index": 0,
                    "n": 0
                }
            ],
            "tx_index": 0,
            "type": 0,
            "value": 1880609,
            "n": 1,
            "script": "0014292738ed3f9466f8eedd8c49e5bb013088a7052b"
        },
        "script": ""
    }
],

此元素缺少prev_out.addr。

您需要首先检查 addr 元素是否存在或将循环包装在 try/except 中。

for transaction in firstjson['txs']:
    ...
    for item in transaction['inputs']:
        address = item.get('prev_out').get('addr')
        if(address == None):
            continue
        payerlist.append(address)
        ...

如果prev_out 不存在，上述操作仍然会失败，因此您应该确认结果中将是什么以及可能是什么。

【讨论】：