Python按StartDate字段对JSON对象数组排序问题排查

需求说明 #

• 遍历JSON中的所有对象数组，若数组内的对象包含StartDate字段，则将该数组按StartDate从最新到最早倒序排序。

JSON示例片段 #

{
    "items": [
        {
            "PersonId": "0000000000000000",
            "PersonNumber": "0000000000",
            "CorrespondenceLanguage": null,
            "BloodType": null,
            "DateOfBirth": "1990-01-01",
            "DateOfDeath": null,
            "CountryOfBirth": null,
            "RegionOfBirth": null,
            "TownOfBirth": null,
            "ApplicantNumber": null,
            "CreatedBy": "CREATOR",
            "CreationDate": "2023-11-23T11:41:21.743000+00:00",
            "LastUpdatedBy": "CREATOR",
            "LastUpdateDate": "2023-12-01T21:36:38.694000+00:00",
            "workRelationships": {
                "items": [
                    {
                        "PeriodOfServiceId": "0",
                        "LegislationCode": "US",
                        "LegalEntityId": "0",
                        "LegalEmployerName": "Employer LLC",
                        "WorkerType": "E",
                        "PrimaryFlag": true,
                        "StartDate": "2013-10-21",
                        "assignments": {
                            "items": [
                                {
                                    "AssignmentId": 300000006167868,
                                    "AssignmentNumber": "A0000-0",
                                    "AssignmentName": "Project Manager",
                                    "ActionCode": "TERMINATION",
                                    "ReasonCode": "TEST",
                                    "EffectiveStartDate": "2022-12-22"
                                }
                            ]
                        }
                    },
                    {
                        "PeriodOfServiceId": "0",
                        "LegislationCode": "US",
                        "LegalEntityId": "0",
                        "LegalEmployerName": "Employer LLC",
                        "WorkerType": "E",
                        "PrimaryFlag": true,
                        "StartDate": "2023-12-08",
                        "assignments": {
                            "items": [
                                {
                                    "AssignmentId": 0,
                                    "AssignmentNumber": "A000000-0",
                                    "AssignmentName": "Project management B1",
                                    "ActionCode": "REHIRE",
                                    "ReasonCode": null,
                                    "EffectiveStartDate": "2023-12-08"
                                }
                            ]
                        }
                    }
                ]
            }
        }
    ]
}

问题代码 #

import json
from datetime import datetime

def main(input):
  adata = json.loads(input['workerData'])
  output_data = sort_arrays_with_StartDate(adata)
  return {'items': output_data}

def sort_arrays_with_StartDate(data):
    if isinstance(data, dict):
        for key, value in data.items():
            if key == 'StartDate' and isinstance(value, list):
                data[key] = sorted(value, key=lambda x: datetime.strptime(x.get('StartDate', ''), '%Y-%m-%d'), reverse=True)
            elif isinstance(value, (dict, list)):
                data[key] = sort_arrays_with_StartDate(value)  # Update the original data
    elif isinstance(data, list):
        for i, item in enumerate(data):
            data[i] = sort_arrays_with_StartDate(item)  # Update the original data
    return data  # Return the updated data

问题分析 #

原代码逻辑完全错误：

• 错误地判断键为StartDate的数组才需要排序，但实际要处理的是数组内对象包含StartDate字段的数组，比如示例中的workRelationships.items
• 递归遍历数组时，仅对数组内的每个对象做递归处理，没有检查当前数组是否需要排序

修正后的代码 #

import json
from datetime import datetime

def main(input):
    adata = json.loads(input['workerData'])
    output_data = sort_arrays_with_StartDate(adata)
    return {'items': output_data}

def sort_arrays_with_StartDate(data):
    if isinstance(data, dict):
        for key, value in data.items():
            data[key] = sort_arrays_with_StartDate(value)
    elif isinstance(data, list):
        # 先处理数组内的嵌套结构
        for i, item in enumerate(data):
            data[i] = sort_arrays_with_StartDate(item)
        # 检查数组内的对象是否包含StartDate字段（假设数组内对象结构一致）
        if data and isinstance(data[0], dict) and 'StartDate' in data[0]:
            try:
                # 按StartDate倒序排序，解析为日期对象确保排序准确
                data.sort(key=lambda x: datetime.strptime(x['StartDate'], '%Y-%m-%d'), reverse=True)
            except ValueError:
                # 处理日期格式错误的情况，不排序直接返回
                pass
    return data

关键修改点 #

1. 调整排序判断逻辑：当遍历到数组时，先检查数组内的对象是否包含StartDate字段，符合条件才执行排序
2. 先处理嵌套再排序：递归处理数组内的所有嵌套结构后，再对当前数组进行排序，避免嵌套结构未处理完成就排序
3. 增加异常处理：防止StartDate格式错误导致程序崩溃

内容的提问来源于stack exchange，提问作者Jonar Ramos