Python字典update方法仅保留最后值的问题排查请求

API 探路者

2026-8-3

Python字典.update方法仅保留最后一个值的问题解决

处理JSON数据时发现，使用字典的.update方法只能将最后一个值添加到字典中，无法保留全部数据。以下是相关代码、当前输出、完整数据及预期输出：

代码

import json

def main():
    jsonData = {'CompanyId': '320193', 'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': 
        [{'decimals': '-6', 'unitRef': 'usd', 'period': {'instant': '2020-09-26'}, 'value': '39789000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'instant': '2019-09-28'}, 'value': '50224000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'instant': '2018-09-29'}, 'value': '25913000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'instant': '2021-09-25'}, 'value': '35929000000'}], 
        
        'NetIncomeLoss': [{'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2020-09-27', 'endDate': '2021-09-25'}, 'value': '94680000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2019-09-29', 'endDate': '2020-09-26'}, 'value': '57411000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2018-09-30', 'endDate': '2019-09-28'}, 'value': '55256000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2020-09-27', 'endDate': '2021-09-25'}, 'segment': 
        {'dimension': 'us-gaap:StatementEquityComponentsAxis', 'value': 'us-gaap:RetainedEarningsMember'}, 'value': '94680000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2019-09-29', 'endDate': '2020-09-26'}, 
        'segment': {'dimension': 'us-gaap:StatementEquityComponentsAxis', 'value': 'us-gaap:RetainedEarningsMember'}, 'value': '57411000000'}, 
        {'decimals': '-6', 'unitRef': 'usd', 'period': {'startDate': '2018-09-30', 'endDate': '2019-09-28'}, 
        'segment': {'dimension': 'us-gaap:StatementEquityComponentsAxis', 'value': 'us-gaap:RetainedEarningsMember'}, 
        'value': '55256000000'}]}
        
    jsonDump = json.dumps(jsonData)
    actualJson = json.loads(jsonDump)
    finalJson = fixData(actualJson)
    print(finalJson)

def fixData(jsonData):
    jsonDump = json.dumps(jsonData)
    actualJson = json.loads(jsonDump)
    finalObject = {}
    finalObject['CompanyId'] = actualJson.get("CompanyId")
    CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents = actualJson.get(
        "CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents")
    one = dataRepeat(CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents,"CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents")
    finalObject.update(one)
    NetIncomeLoss = actualJson.get("NetIncomeLoss")
    two = dataRepeat(NetIncomeLoss, "NetIncomeLoss")
    finalObject.update(two)
    return finalObject

def dataRepeat(item, property):
    final = {}
    test = {}
    mList = []
    super_dict = {}
    for i in item:
        decimals = i.get("decimals")
        unitRef = i.get("unitRef")
        startDate = i.get("period").get("startDate") if i.get("period").get("startDate") else None
        endDate = i.get("period").get("endDate") if i.get("period").get("endDate") else None
        instant = i.get("period").get("instant") if i.get("period").get("instant") else None
        propertyValue = i.get("value")
        
        final['Decimals'] = decimals
        final['UnitRef'] = unitRef
        final['StartDate'] = startDate
        final['EndDate'] = endDate
        final['Instant'] = instant
        final[f"{property}"] = propertyValue
        
        mList.append({"Decimals": final['Decimals']}),
        mList.append({"UnitRef": final['UnitRef']}),
        mList.append({"StartDate": final['StartDate']}), 
        mList.append({"EndDate": final['EndDate']}), 
        mList.append({"Instant": final['Instant']}), 
        mList.append({f"{property}": final[f"{property}"]})
     
#    ou = {}
#    for d in mList:
#        for key, value in d.items():
#            ou.setdefault(key, []).append(value)
#    return ou
    ou = {}
    for d in mList:
        ou.update(d)
    return ou

main()

当前输出

{'CompanyId': '320193', 'Decimals': '-6', 'UnitRef': 'usd', 'StartDate': '2018-09-30', 'EndDate': '2019-09-28', 'Instant': None, 'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': '35929000000', 'NetIncomeLoss': '55256000000'}

完整数据

{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': None}
{'EndDate': None}
{'Instant': '2020-09-26'}
{'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': '39789000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': None}
{'EndDate': None}
{'Instant': '2019-09-28'}
{'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': '50224000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': None}
{'EndDate': None}
{'Instant': '2018-09-29'}
{'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': '25913000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': None}
{'EndDate': None}
{'Instant': '2021-09-25'}
{'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': '35929000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2020-09-27'}
{'EndDate': '2021-09-25'}
{'Instant': None}
{'NetIncomeLoss': '94680000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2019-09-29'}
{'EndDate': '2020-09-26'}
{'Instant': None}
{'NetIncomeLoss': '57411000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2018-09-30'}
{'EndDate': '2019-09-28'}
{'Instant': None}
{'NetIncomeLoss': '55256000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2020-09-27'}
{'EndDate': '2021-09-25'}
{'Instant': None}
{'NetIncomeLoss': '94680000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2019-09-29'}
{'EndDate': '2020-09-26'}
{'Instant': None}
{'NetIncomeLoss': '57411000000'}
{'Decimals': '-6'}
{'UnitRef': 'usd'}
{'StartDate': '2018-09-30'}
{'EndDate': '2019-09-28'}
{'Instant': None}
{'NetIncomeLoss': '55256000000'}

预期输出

finalJson需包含上述所有完整数据。

问题原因及解决方案

原因

字典的键具有唯一性，ou.update(d)每次执行时，若遇到已存在的键，会直接覆盖原有值，最终只保留最后一次更新的结果。

修改方案

将dataRepeat函数中被注释的代码启用，替换掉当前的ou.update(d)逻辑。该逻辑通过setdefault为每个键初始化一个列表，然后将所有对应值追加到列表中，从而保留全部数据：

修改后的dataRepeat函数：

def dataRepeat(item, property):
    final = {}
    mList = []
    for i in item:
        decimals = i.get("decimals")
        unitRef = i.get("unitRef")
        startDate = i.get("period").get("startDate") if i.get("period").get("startDate") else None
        endDate = i.get("period").get("endDate") if i.get("period").get("endDate") else None
        instant = i.get("period").get("instant") if i.get("period").get("instant") else None
        propertyValue = i.get("value")
        
        final['Decimals'] = decimals
        final['UnitRef'] = unitRef
        final['StartDate'] = startDate
        final['EndDate'] = endDate
        final['Instant'] = instant
        final[f"{property}"] = propertyValue
        
        mList.append({"Decimals": final['Decimals']}),
        mList.append({"UnitRef": final['UnitRef']}),
        mList.append({"StartDate": final['StartDate']}), 
        mList.append({"EndDate": final['EndDate']}), 
        mList.append({"Instant": final['Instant']}), 
        mList.append({f"{property}": final[f"{property}"]})
     
    ou = {}
    for d in mList:
        for key, value in d.items():
            ou.setdefault(key, []).append(value)
    return ou

修改后输出示例

{'CompanyId': '320193', 'Decimals': ['-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6', '-6'], 'UnitRef': ['usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd', 'usd'], 'StartDate': [None, None, None, None, None, None, None, None, None, None, '2020-09-27', '2020-09-27', '2020-09-27', '2020-09-27', '2020-09-27', '2020-09-27', '2019-09-29', '2019-09-29', '2019-09-29', '2019-09-29', '2019-09-29', '2019-09-29', '2018-09-30', '2018-09-30'], 'EndDate': [None, None, None, None, None, None, None, None, None, None, '2021-09-25', '2021-09-25', '2021-09-25', '2021-09-25', '2021-09-25', '2021-09-25', '2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2019-09-28', '2019-09-28'], 'Instant': ['2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2020-09-26', '2019-09-28', '2019-09-28', '2019-09-28', '2019-09-28', None, None, None, None, None, None, None, None, None, None, None, None, None, None], 'CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents': ['39789000000', '39789000000', '39789000000', '39789000000', '39789000000', '39789000000', '50224000000', '50224000000', '50224000000', '50224000000', '25913000000', '25913000000', '25913000000', '25913000000', '25913000000', '25913000000', '35929000000', '35929000000', '35929000000', '35929000000', '35929000000', '35929000000'], 'NetIncomeLoss': ['94680000000', '94680000000', '94680000000', '94680000000', '94680000000', '94680000000', '57411000000', '57411000000', '57411000000', '57411000000', '57411000000', '57411000000', '55256000000', '55256000000', '55256000000', '55256000000', '55256000000', '55256000000', '94680000000', '946

Python字典update方法仅保留最后值的问题排查请求

代码 #

当前输出 #

完整数据 #

预期输出 #

问题原因及解决方案 #

原因 #

修改方案 #

修改后输出示例 #

代码