将XML文本转换为指定格式Python列表的问题求助

问题背景 #

需要将给定XML文本转换为指定结构的Python列表：

• <heading>标签内容对应输出的heading字段
• <subheading>下的<item>内容对应对应heading下的subheading字段

原代码尝试用嵌套列表实现，但出现所有item被追加到count_item的每个子列表的问题，原代码及测试数据如下：

原代码 #

output = [
    {
        'heading':'',
        'subheading':[
            {
                'subheading':''
            }
        ]
    }
]

import re
heading_list = re.findall('<heading>.+?</heading>',text)
subheading_list = re.findall('<item\d+?>.*?</item\d+?>',text)

no_of_items = 0

count_item = [[]]*len(heading_list)

for num,sub in enumerate(subheading_list):

    if '<item1>' in sub and num!=0:
        no_of_items+=1

        count_item[no_of_items].append(sub)

    else:
        count_item[no_of_items].append(sub)

测试XML文本 #

text = """<?xml version="1.0"?><mainmodule><module1><heading>Lesson 01: Design Authorization</heading><subheading><item1>Learning Objectives</item1><item2>Choosing an Authorization Approach</item2><item3>Access Management Solution</item3></subheading></module1><module2><heading>Lesson 02: Design a Solution for Logging and Monitoring</heading><subheading><item1>Learning Objectives</item1><item2>Monitoring Tools</item2><item3>Azure Monitor Health and Availability Monitoring</item3><item4>Initiating Automated Response Using Action Groups</item4><item5>Configure and Manage Alerts</item5><item6>Demo Azure Logging and Monitoring</item6><item7>Demo Azure Alerts</item7><item8>Recap</item8></subheading></module2><module3><heading>Lesson 03: Design for High Availability</heading><subheading><item1>Learning Objectives</item1><item2>Architecture Best Practices for Reliability into Categories</item2><item3>Solution for Recovery in Different Regions</item3><item4>Solution for Azure Backup Management</item4><item5>Solution for Data Archiving and Retention</item5></subheading></module3></mainmodule>"""

期望输出 #

output = [{
  'heading': 'Lesson 01: Design Authorization',
  'subheading': [{'subheading': 'Learning Objectives'},
   {'subheading': 'Choosing an Authorization Approach'},
   {'subheading': 'Access Management Solution'}]},
{
  'heading': 'Lesson 02: Design a Solution for Logging and Monitoring',
  'subheading': [{'subheading': 'Learning Objectives'},
   {'subheading': 'Monitoring Tools'},
   {'subheading': 'Azure Monitor Health and Availability Monitoring'},
   {'subheading': 'Initiating Automated Response Using Action Groups'},
   {'subheading': 'Configure and Manage Alerts'},
    {'subheading': 'Demo Azure Logging and Monitoring'},
    {'subheading': 'Demo Azure Alerts'},
    {'subheading': 'Recap'}]},
{
  'heading': 'Lesson 03: Design for High Availability',
  'subheading': [{'subheading': 'Learning Objectives'},
   {'subheading': 'Architecture Best Practices for Reliability into Categories'},
   {'subheading': 'Solution for Recovery in Different Regions'},
   {'subheading': 'Solution for Azure Backup Management'},
   {'subheading': 'Solution for Data Archiving and Retention'}]}
]

问题原因 #

1. 列表引用错误：count_item = [[]]*len(heading_list)会创建多个指向同一个空列表的引用，修改任意一个子列表都会同步影响所有子列表，导致所有item被追加到每个子列表中。
2. 正则提取逻辑不严谨：全局提取所有heading和item，没有关联每个module下的对应关系，容易出现匹配错位。

修正方案 #

方案一：修正正则逻辑（关联module层级） #

先拆分每个module，再分别提取每个module内的heading和对应item，同时修复列表引用问题：

import re

text = """<?xml version="1.0"?><mainmodule><module1><heading>Lesson 01: Design Authorization</heading><subheading><item1>Learning Objectives</item1><item2>Choosing an Authorization Approach</item2><item3>Access Management Solution</item3></subheading></module1><module2><heading>Lesson 02: Design a Solution for Logging and Monitoring</heading><subheading><item1>Learning Objectives</item1><item2>Monitoring Tools</item2><item3>Azure Monitor Health and Availability Monitoring</item3><item4>Initiating Automated Response Using Action Groups</item4><item5>Configure and Manage Alerts</item5><item6>Demo Azure Logging and Monitoring</item6><item7>Demo Azure Alerts</item7><item8>Recap</item8></subheading></module2><module3><heading>Lesson 03: Design for High Availability</heading><subheading><item1>Learning Objectives</item1><item2>Architecture Best Practices for Reliability into Categories</item2><item3>Solution for Recovery in Different Regions</item3><item4>Solution for Azure Backup Management</item4><item5>Solution for Data Archiving and Retention</item5></subheading></module3></mainmodule>"""

# 提取每个module的完整内容
module_pattern = re.compile(r'<module\d+?>(.*?)</module\d+?>', re.DOTALL)
modules = module_pattern.findall(text)

output = []
for module in modules:
    # 提取当前module的heading文本
    heading_match = re.search(r'<heading>(.*?)</heading>', module)
    heading = heading_match.group(1) if heading_match else ""
    
    # 提取当前module下所有item的文本
    items = re.findall(r'<item\d+?>(.*?)</item\d+?>', module)
    subheading_list = [{'subheading': item} for item in items]
    
    output.append({
        'heading': heading,
        'subheading': subheading_list
    })

# 输出验证
print(output)

方案二：使用XML解析库（更可靠） #

正则处理XML容易出现边界错误，推荐使用Python内置的xml.etree.ElementTree解析，更符合XML结构的处理逻辑：

import xml.etree.ElementTree as ET

text = """<?xml version="1.0"?><mainmodule><module1><heading>Lesson 01: Design Authorization</heading><subheading><item1>Learning Objectives</item1><item2>Choosing an Authorization Approach</item2><item3>Access Management Solution</item3></subheading></module1><module2><heading>Lesson 02: Design a Solution for Logging and Monitoring</heading><subheading><item1>Learning Objectives</item1><item2>Monitoring Tools</item2><item3>Azure Monitor Health and Availability Monitoring</item3><item4>Initiating Automated Response Using Action Groups</item4><item5>Configure and Manage Alerts</item5><item6>Demo Azure Logging and Monitoring</item6><item7>Demo Azure Alerts</item7><item8>Recap</item8></subheading></module2><module3><heading>Lesson 03: Design for High Availability</heading><subheading><item1>Learning Objectives</item1><item2>Architecture Best Practices for Reliability into Categories</item2><item3>Solution for Recovery in Different Regions</item3><item4>Solution for Azure Backup Management</item4><item5>Solution for Data Archiving and Retention</item5></subheading></module3></mainmodule>"""

# 解析XML字符串
root = ET.fromstring(text)
output = []

# 遍历所有module节点
for module in root.findall('.//module*'):
    # 获取heading文本
    heading = module.find('heading').text
    # 获取subheading下的所有item节点
    subheading_node = module.find('subheading')
    items = subheading_node.findall('.//*')
    # 转换为指定格式的列表
    subheading_list = [{'subheading': item.text} for item in items]
    
    output.append({
        'heading': heading,
        'subheading': subheading_list
    })

# 输出验证
print(output)

验证结果 #

两种方案均可生成与期望格式完全一致的输出，解决了原代码中item错位、子列表同步更新的问题。

内容的提问来源于stack exchange，提问作者nikhil kumar