如何用Regex从字符串中精准提取指定键值对（如firstName）

抓取到一段包含多组JSON键值对的网页字符串，想要提取其中firstName、lastName等字段生成列表。尝试用正则表达式re.findall('"firstName":"(.*)\S$",st)时，匹配结果附带了多余内容，如何让正则在姓名的结束引号位置停止匹配？

示例字符串代码：

st = '{"accountId":405266,"firstName":"Quaran","lastName":"McPherson","accountIdentifier":"StudentAthlete","profilePicUrl":"https://pbs.twimg.com/profile_images/1331475329014181888/4z19KrCf.jpg","networkProfileCode":"quaran-mcpherson","hasDeals":true,"activityMin":11,"sports":["Men\'s Basketball","Basketball"],"currentTeams":["Nebraska Cornhuskers"],"previousTeams":[],"facebookReach":null,"twitterReach":619,"instagramReach":0,"linkedInReach":null},{"accountId":375964,"firstName":"Micole","lastName":"Cayton","accountIdentifier":"StudentAthlete","profilePicUrl":"https://opendorsepr.blob.core.windows.net/media/375964/20220622223838_46dbe3fd-a683-436b-84d4-90c84a5af35f.jpg","networkProfileCode":"micole-cayton","hasDeals":true,"activityMin":16,"sports":["Basketball","Women\'s Basketball"],"currentTeams":["Minnesota Golden Gophers"],"previousTeams":["Cal Berkeley Golden Bears"],"facebookReach":0,"twitterReach":1273,"instagramReach":5700,"linkedInReach":null}'

一、优化正则表达式 #

之前的正则用(.*)贪婪匹配，会尽可能抓取到最后一个符合条件的位置，导致多余内容。可以通过两种方式修正：

方式1：非贪婪匹配 #

将.*改为.*?，让正则匹配到第一个结束引号"就停止：

import re

# 提取firstName
first_names = re.findall(r'"firstName":"(.*?)"', st)
# 提取lastName
last_names = re.findall(r'"lastName":"(.*?)"', st)

print(first_names)  # 输出: ['Quaran', 'Micole']
print(last_names)   # 输出: ['McPherson', 'Cayton']

方式2：字符集限定匹配范围 #

因为姓名不会包含&，而结束引号的开头是&，直接匹配非&的所有字符，精准停止在结束引号前：

first_names = re.findall(r'"firstName":"([^&]+)"', st)
last_names = re.findall(r'"lastName":"([^&]+)"', st)

这种方式匹配效率更高，也能避免意外匹配。

二、转为JSON解析（更推荐） #

正则处理JSON格式数据容易踩坑（比如字段顺序变化、特殊字符转义等），更稳妥的方式是先将字符串转为合法JSON，再用Python内置json模块解析：

import json

# 1. 替换转义引号为标准双引号，包装成JSON数组
processed_str = '[' + st.replace('"', '"') + ']'
# 2. 解析JSON数据
data_list = json.loads(processed_str)

# 3. 提取目标字段
first_names = [item['firstName'] for item in data_list]
last_names = [item['lastName'] for item in data_list]

print(first_names)  # 输出: ['Quaran', 'Micole']
print(last_names)   # 输出: ['McPherson', 'Cayton']

这种方法能应对各种复杂场景，比如姓名含特殊字符、JSON结构调整等，通用性更强。

内容的提问来源于stack exchange，提问作者Rithwik Sivadasan