Return the first occurrence using Regex [closed] - regex

Question

Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 1 year ago.
Improve this question
I have the following expression:
[Document[_id=5f9ecf8ca9bec5549493ba7d,·policy_name=xxx,·is_mobile=false, Document[_id=6090fead53bc363849fce989,·policy_name=yyy,·is_mobile=true, Document[_id=619cf036761c281e3ad12327,·policy_name=zzz,·is_mobile=false, Document[_id=619cf729ea016d1e3336e903,·policy_name=xyz,·is_mobile=false]
I would like to capture ONLY the first Document id (i.e- 5f9ecf8ca9bec5549493ba7d).
i tried this regex- (?<=Document\[_id=).*?[^,]* BUT it will return all the Document id's.
1).how can i capture the first / second (Nth match) of document id from the expression?
2). is it possible to do regex AND operator to find the Document id with "is_mobile=true"?
(i.e 5f9ecf8ca9bec5549493ba7d & true)
would really appreciate any help
EDIT:
i'm using https://regex101.com/
this is the link in which i tried to capture the first / second (nth occurance of Document id ( i need only the number) - https://regex101.com/r/ZnYRhq/1

Answer 1

There is not language listed, but one approach could be using a capture group for the value that you want, and start the pattern with an anchor ^ to assert the start of the string.
For the first Document id:
^.*?\bDocument\[_id=([^\]\[\s,]+)
Regex demo
For the first Document id that has is_mobile=true (assuming that the order of the key-value pairs is as given in the example and is within the same opening and closing square brackets)
^.*?\bDocument\[_id=([^\]\[\s,]+),[^\]\[]*\bis_mobile=true\b
The pattern matches:
^ Start of string
.*?\bDocument\[_id= Match the first occurrence of Document[_id=
( Capture group 1
[^\]\[\s,]+ Match 1+ times any char except ] [ whitespace char or ,
) Close group 1
,[^\]\[]* Match a comma and optional chars other than ] and [
\bis_mobile=true\b Match is_mobile=true between word boundaries
Regex demo
Or using lookarounds for a single (not global) match:
(?<=Document\[_id=)[^,]*(?=,[^][]*\bis_mobile=true\b)
Regex demo

Answer 2

How about this one?
(?:^\[Document\[_id=)([^,]+) for the first?
For n-th you need to use capturing group but how to do this is language/framework dependent.

Answer 3

txt="""
[Document[_id=5f9ecf8ca9bec5549493ba7d,·policy_name=xxx,·is_mobile=false, Document[_id=6090fead53bc363849fce989,·policy_name=yyy,·is_mobile=true, Document[_id=619cf036761c281e3ad12327,·policy_name=zzz,·is_mobile=false, Document[_id=619cf729ea016d1e3336e903,·policy_name=xyz,·is_mobile=false]
"""
print([i.split('=')[1].strip(' ') for i in txt.split(',') if '_id' in i ][0])
output:
5f9ecf8ca9bec5549493ba7d