python to search and update string with regex

Question

I have below string, I am able to grab the \'text\' what I wanted to (text is warped between pattern). code is give below,

val1 = \'[{"vmd         


        

Answer 1

You can do this by using backreferences in combination with re.sub:

import re
val1 = '[{"vmdId":"Text1","vmdVersion":"text2","vmId":"text3"},{"vmId":"text4","vmVersion":"text5","vmId":"text6"}]'

ansstring = re.sub(r'(?<=:")([^(]*)', r'new\g<1>' , val1)

print ansstring

\g<1> is the text which is in the first ().

EDIT

Maybe a better approach would be to decode the string, change the data and encode it again. This should allow you to easier access the values.

import sys

# python2 version
if sys.version_info[0] < 3:
    import HTMLParser
    html = HTMLParser.HTMLParser()
    html_escape_table = {
        "&": "&",
        '"': """,
        "'": "'",
        ">": ">",
        "<": "<",
        }

    def html_escape(text):
        """Produce entities within text."""
        return "".join(html_escape_table.get(c,c) for c in text)

    html.escape = html_escape
else:
    import html

import json

val1 = '[{"vmdId":"Text1","vmdVersion":"text2","vmId":"text3"},{"vmId":"text4","vmVersion":"text5","vmId":"text6"}]'
print(val1)

unescaped = html.unescape(val1)
json_data = json.loads(unescaped)
for d in json_data:
    d['vmId'] = 'new value'

new_unescaped = json.dumps(json_data)
new_val = html.escape(new_unescaped)
print(new_val)

I hope this helps.