比特币交易映射引发 KeyError

Question

I have the following piece of code, which seems to run until line 36 recipientlist.append(target["addr"]) and then throws the error KeyError: 'addr'

However 'addr' seems to be in the data so not sure what the issue is

Can someone please help?

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)

Answer 1

While addr is in your data, it's not in every inputs element. Check the very last element in txs , you'll see that inputs is:

"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": ""
    }
],

This element lacks the presence of prev_out . addr .

You will need to first check if the addr element exists or wrap your loop in a try/except .

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

The above would still fail if prev_out didn't exist, so you should confirm what will be in the result and what might be.