Extracting Key Value pairs from a String using Regex

Your string seems JSON array, you can easily parse json in any language if it's valid. To make your string valid add '[' at first and ']' at last of your string then parse the JSON in your language. Such as

JavaScript:

JSON.parse(st)

Python:

import json
dict = json.loads(st)

Regular expression:

if you strictly wish to parse using regular expression use:

/(?:\"|\')(?<key>[\w\d]+)(?:\"|\')(?:\:\s*)(?:\"|\')?(?<value>[\w\s-]*)(?:\"|\')?/gm

Try this:

(?<="firstName":")[^"\r\n]+

(?<="firstName":") go to the point where "firstName":" appeasrs in the string,

[^"\r\n]+ then match one or more character except ", \r and \n. not to cross the second double quote of the firstName value and not to cross any newline.

See regex demo.

See python demo.

Try this regex (?<=\"firstName\":\").*?(?=\"). The ? in the middle makes it a lazy match, so that it stops matching as soon as it finds a " character.

I want to add that that with backtracking, there can be an exponential performance penalty. I can do something like this "firstName":"(.*?)" and extract the capturing group so that there will only a linear performance penalty.

Regex: https://regex101.com/r/uM2l8M/1

Python code

import re
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}'
pattern = re.compile('"firstName":"(.*?)"')

for match in pattern.finditer(st):
    print(match.group(1))