Xử lý XML trong Python với ElementTree và DOM

Mô tả

Python cung cấp 2 cách chính parse XML: ElementTree (nhẹ, Pythonic) và DOM (tiêu chuẩn W3C, nặng hơn).

File XML mẫu (tutorials.xml)

<?xml version="1.0"?>
<Tutorials>
  <Tutorial id="Tu101">
    <author>Vicky, Matthew</author>
    <title>Geo-Spatial Data Analysis</title>
    <stream>Python</stream>
    <price>4.95</price>
    <publish_date>2020-07-01</publish_date>
    <description>Learn geo Spatial data Analysis using Python.</description>
  </Tutorial>
  <Tutorial id="Tu102">
    <author>Bolan, Kim</author>
    <title>Data Structures</title>
    <stream>Computer Science</stream>
    <price>12.03</price>
    <publish_date>2020-1-19</publish_date>
    <description>Learn Data structures using different programming languages.</description>
  </Tutorial>
  <Tutorial id="Tu103">
    <author>Sora, Everest</author>
    <title>Analytics using Tensorflow</title>
    <stream>Data Science</stream>
    <price>7.11</price>
    <publish_date>2020-1-19</publish_date>
    <description>Learn Data analytics using Tensorflow.</description>
  </Tutorial>
</Tutorials>

1. ElementTree (Khuyên dùng)

Đọc toàn bộ nội dung

import xml.etree.ElementTree as ET

tree = ET.parse('tutorials.xml')
root = tree.getroot()

print("Danh sách Tutorial:")
for tutorial in root:
    print(f"\n--- Tutorial {tutorial.attrib.get('id')} ---")
    for child in tutorial:
        print(f"  {child.tag}: {child.text}")

Lấy attribute

for tutorial in root.iter('Tutorial'):
    print(tutorial.attrib)  # {'id': 'Tu101'}

Lọc với XPath (findall)

# Tìm Tutorial có price = 12.03
for tutorial in root.findall("./Tutorial[price='12.03']"):
    print(tutorial.attrib)  # {'id': 'Tu102'}

# Tìm tất cả title
titles = root.findall('.//title')
for t in titles:
    print(t.text)

Tạo/Sửa XML

# Tạo mới
new_tut = ET.SubElement(root, 'Tutorial', id='Tu104')
ET.SubElement(new_tut, 'title').text = 'New Tutorial'
ET.SubElement(new_tut, 'price').text = '9.99'

# Ghi file
tree.write('tutorials_updated.xml', encoding='utf-8', xml_declaration=True)

2. DOM API (xml.dom.minidom)

from xml.dom.minidom import parse

DOMTree = parse('tutorials.xml')
collection = DOMTree.documentElement

tutorials = collection.getElementsByTagName("Tutorial")
for tut in tutorials:
    stream = tut.getElementsByTagName('stream')[0]
    price = tut.getElementsByTagName('price')[0]
    print(f"Stream: {stream.childNodes[0].data}, Price: {price.childNodes[0].data}")

So sánh

3. Xử lý XML lớn: iterparse (Streaming)

# Cho file XML rất lớn, không load hết vào RAM
for event, elem in ET.iterparse('large_file.xml', events=('start', 'end')):
    if event == 'end' and elem.tag == 'Tutorial':
        # Xử lý elem
        print(elem.find('title').text)
        # Quan trọng: clear để giải phóng bộ nhớ
        elem.clear()