Regex to Extract Last Part of URL that Contains User ID Strings - regex

Question

I'm having a hard time figuring this one out and could use some help.
I'm using Google Analytics filters to reduce the number of unique pages being reported in our app by stripping out ID strings from the URLs that are coming in.
What I need is a regex that will look for URLs that have these IDs in the URL. Here's what sets them apart from the rest of the URL:
ID strings are always the last part of the URL
ID strings always contain both letters and numbers
ID strings are always either 16- or 32-characters in length
ID strings can show up twice in a URL
ID strings can end with either a "/" or without
Here are some example URLs that show how they appear in our reporting:
/app/6be031b9672be9b5/
/app/admin/client/settings/6be031b9672be9b5
/app/subscribers/ea33fb38c9efc4dc0367819f23434f99/
/app/subscribers/customfieldsettings/0359c487066727ae/
/app/reports/6fa92d36be0e6c16/dc5aa096fba9cbb97eea1dae616d4b3c/
The second part of my question is that this regex should also group everything before these ID strings into a capturing group so that I can call that group later on in the filter, effectively stripping out these ID strings to look like the following:
/app/6be031b9672be9b5/ --> /app/
/app/subscribers/ea33fb38c9efc4dc0367819f23434f99/ --> /app/subscribers/
etc.
I've tried a couple different approaches but none seem to work perfectly, so I could really use the help, thank you!

Answer 1

Here's a solution:
^(.*?)(?:\/[a-zA-Z0-9]{16}|\/[a-zA-Z0-9]{32}){0,2}\/?$
Demo
This will remove the last part or 2 parts of URLs which are 16 or 32 characters long and contain only letters and digits.
You can make sure these parts contain both letters and numbers like this, if the tool supports lookaheads:
^(.*?)(?:\/(?=.{0,15}?\d)(?=.{0,15}?[a-zA-Z])[a-zA-Z0-9]{16}|\/(?=.{0,31}?\d)(?=.{0,31}?[a-zA-Z])[a-zA-Z0-9]{32}){0,2}\/?$
Demo
This adds assertions to the pattern.
Breakdown:
^(.*?) # Start of URL
(?:
\/ # a slash
(?=.{0,15}?\d) # check there's a digit at most 16 chars ahead
(?=.{0,15}?[a-zA-Z]) # check there's a letter at most 16 chars ahead
[a-zA-Z0-9]{16} # check the next 16 chars are digits or letters
| # .. or:
\/ # a slash
(?=.{0,31}?\d) # check there's a digit at most 32 chars ahead
(?=.{0,31}?[a-zA-Z]) # check there's a letter at most 32 chars ahead
[a-zA-Z0-9]{32} # check the next 32 chars are digits or letters
){0,2} # .. at most 2 times
\/?$ # optional slash at end

Answer 2

This will do it:
([a-z0-9]+)(?:\/?$)
Demo
Explanation:
([a-z0-9]+) matches and captures the alphanumeric part
(?:\/?$) looks for (but doesn't match or capture) the optional final / and then the end of the string ($)

Answer 3

modified - totally missed that can be 1 or 2 id's at the end thing.
Oh well, revised fwiw.
# (?i)^(.*?)/((?:(?=[^/]{0,31}[a-f])(?=[^/]{0,31}[0-9])(?:[a-f0-9]{16}|[a-f0-9]{32})(?:(?:/[a-z])?/?$|/)){1,2})$
(?i) # Case insensitive modifier
^ # BOS, begin the ride ..
( .*? ) # (1), Kreep up on the first ID
/ # Trim this / junk
( # (2 start), 1-2 ID's separated by a /
(?:
(?= [^/]{0,31} [a-f] ) # Use largest range (32), Must be a lettr AND number
(?= [^/]{0,31} [0-9] )
(?: # One of 16 or 32 length
[a-f0-9]{16}
| [a-f0-9]{32}
)
(?:
(?: / [a-z] )? # optional / letter
/? $ # /? EOS for end of 1 or 2
| # or,
/ # / between 2 only
)
){1,2}
) # (2 end)
$ # EOS, rides over !!
Sample output:
** Grp 0 - ( pos 195 , len 63 )
/app/reports/6fa92d36be0e6c16/dc5aa096fba9cbb97eea1dae616d4b3c/
** Grp 1 - ( pos 195 , len 12 )
/app/reports
** Grp 2 - ( pos 208 , len 50 )
6fa92d36be0e6c16/dc5aa096fba9cbb97eea1dae616d4b3c/