如何使用bs4从HTML中提取class和id属性？解决KeyError问题

问题原因 #

你提供的两段<p>标签中，第二个标签没有id属性，取而代之的是data-id属性。直接通过pr['id']访问不存在的属性会触发KeyError。

修复方案 #

方案1：使用get()方法安全获取属性

BeautifulSoup的Tag对象支持用get()方法获取属性，当属性不存在时会返回默认值（比如None），避免报错：

from bs4 import BeautifulSoup

html = '''<p transform="translate(3,15)" class="SoccerPlayer SoccerPlayer-1 Soccer-Team  Outcome-Positive" id="12-8-3">
<p transform="translate(89,20)" class="SoccerPlayer SoccerPlayer-514 Soccer-Team Outcome-Positive" data-id="12-9-229">'''

soup = BeautifulSoup(html, 'html.parser')
for pr in soup.find_all("p"):
    class_attr = pr['class']
    id_attr = pr.get('id')
    data_id_attr = pr.get('data-id')
    print(f"class: {class_attr}, id: {id_attr}, data-id: {data_id_attr}")

方案2：先检查属性是否存在再访问

通过in操作符判断属性是否存在，再进行访问：

from bs4 import BeautifulSoup

html = '''<p transform="translate(3,15)" class="SoccerPlayer SoccerPlayer-1 Soccer-Team  Outcome-Positive" id="12-8-3">
<p transform="translate(89,20)" class="SoccerPlayer SoccerPlayer-514 Soccer-Team Outcome-Positive" data-id="12-9-229">'''

soup = BeautifulSoup(html, 'html.parser')
for pr in soup.find_all("p"):
    class_attr = pr['class']
    id_attr = pr['id'] if 'id' in pr.attrs else None
    data_id_attr = pr['data-id'] if 'data-id' in pr.attrs else None
    print(f"class: {class_attr}, id: {id_attr}, data-id: {data_id_attr}")

补充说明 #

如果需要提取所有标识性ID（包括id和data-id），可以合并处理：

from bs4 import BeautifulSoup

html = '''<p transform="translate(3,15)" class="SoccerPlayer SoccerPlayer-1 Soccer-Team  Outcome-Positive" id="12-8-3">
<p transform="translate(89,20)" class="SoccerPlayer SoccerPlayer-514 Soccer-Team Outcome-Positive" data-id="12-9-229">'''

soup = BeautifulSoup(html, 'html.parser')
for pr in soup.find_all("p"):
    class_attr = pr['class']
    player_id = pr.get('id') or pr.get('data-id')
    print(f"class: {class_attr}, player_id: {player_id}")

内容的提问来源于stack exchange，提问作者JayRSP