regular expression to extract json fields

[Luis Pecht]

Hi, kindly asking for a hand , here.


suppose, a simple Json object:


{"title":"Title", {"data":"Data", {"foo": "Bar"}}

and a regular expression:

(?<="foo"\ *:\ *")(?:\"|[^"])*

that matches "Bar" value.

{"title":"Title", {"data":"Data", {"foo": "Bar"}}


I have not been able to apply that in Stata

clear
input str51 json
`"{"title":"Title",  {"data":"Data", {"foo": "Bar"}}"'
end

. gen str9 foo = ustrregexs(0) if ustrregexm( json ,`"(?<="foo"\ *:\ *")(?:\\"|[^"])*"')
(1 missing value generated)


. list

     +----------------------------------------------------------+
     |                                               json   foo |
     |----------------------------------------------------------|
  1. | {"title":"Title",  {"data":"Data", {"foo": "Bar"}}       |
     +---------------------------------------------------------

I guess I am not escaping "foo" double quotes correctly.

thanks

[Andrew Musau]

clear
input str51 json
`"{"title":"Title",  {"data":"Data", {"foo": "Bar"}}"'
end


gen wanted = ustrregexra(json, `".*\{"foo":\s(.*)\}\}"', "$1")

Res.:

. l

     +-------------------------------------------------------------+
     |                                               json   wanted |
     |-------------------------------------------------------------|
  1. | {"title":"Title",  {"data":"Data", {"foo": "Bar"}}    "Bar" |
     +-------------------------------------------------------------+