Regex problems matching invalid json string

Question

I have a truncated/invalid json string that I need to extract a GUIID from. However I am unable to use double quotes in my regex match.

import re

input = '{\"event\":{\"header\":{\"transactions\":{\"localTransactions\":{\"id\":\"11111111-239e-4f86-9f5a-111111111111\",\"sourceApplication\":{\"name\":\"worker\",\"host\":\"worker-67bcdfc6bb\"},\"createdAt\":\"2021-04-08T14:05:03.571Z\",\"websocketId\":\"abc=\"},\"localTransaction\":[]},\"user\":null,\"interceptorId\":null},\"payload\":{\"operation\":{\"operationCode\":\"500\",\"applicationErrorCode\":\"202\",\"operationMessage\":\"Exception\",\"status\":\"failure\",\"reason\":\"Failure - Failed to ggg.\"},\"response\":{\"operation\":{\"operationCode\":\"500\",\"applicationErrorCode\":\"CP0202\",\"operationMessage\":\"Exceptio. We are working on it and will in [TRUNCATED]'

regex_pattern = '(?<=localTransactions)(.*)(?=sourceApplication)' #This works but it is not ideal

regex_result = re.search(regex_pattern, input)    
if regex_result:
  print("We have a match!")
  print(regex_result.group())
else:
  print("No match")

This code results in the following match: \":{\"id\":\"11111111-239e-4f86-9f5a-111111111111\",\"

But what I actually want is only the guid value, 11111111-239e-4f86-9f5a-111111111111 So I have been experimenting with various regex patterns such as this:

 regex_pattern = '(?<=localTransactions\":{\")(.*)(?=\",\"sourceApplication)'

But using this finds nothing at all.

How to use regex with double quotes/json strings?

user_3832970 · Answer

First, you need to name the string variable as something like text, input is a built-in.

You can use

regex_pattern = r'localTransactions\":{\"id\":\"(.*?)\",\"sourceApplication'

and retrieve the match you need using

regex_result = re.search(regex_pattern, text)    
if regex_result:
  print("We have a match!", regex_result.group(1), sep="
")
else:
  print("No match")

See the regex demo and the Python demo. Output:

We have a match!
11111111-239e-4f86-9f5a-111111111111

Regex problems matching invalid json string

1 Answers