How to find a particular json value by key?

Question

There is a json like this:

{
  \"P1\": \"ss\",
  \"Id\": 1234,
  \"P2\": {
      \"P1\": \"cccc\"
  },
  \"P3\": [
      {
          \"P1\": \"aaa\"
      }
         


        

Answer 1

Bearing in mind that json is simply a string, using regular expressions with look-ahead and look-behind can accomplish this task very quickly.

Typically, the json would have been extracted from a request to external api, so code to show how that would work has been included but commented out.

import re
#import requests
#import json

#r1 = requests.get( ... url to some api ...)
#JSON = str(json.loads(r1.text))
JSON = """
 {
  "P1": "ss",
  "Id": 1234,
  "P2": {
      "P1": "cccc"
  },
  "P3": [
     {
          "P1": "aaa"
     }
  ]
 }
"""
rex1  = re.compile('(?<=\"P1\": \")[a-zA-Z_\- ]+(?=\")')
rex2 = rex1.findall(JSON)  
print(rex2)

#['ss', 'cccc', 'aaa']