Regex: validate a URL path with no query params

Question

I'm not a regex expert and I'm breaking my head trying to do one that seems very simple and works in python 2.7: validate the path of an URL (no hostname) without the query string. In other words, a string that starts with /, allows alphanumeric values and doesn't allow any other special chars except these: /, ., -

I found this post that is very similar to what I need but for me isn't working at all, I can test with for example aaa and it will return true even if it doesn't start with /.

The current regex that I have kinda working is this one:

[^/+a-zA-Z0-9.-]

but it doesn't work with paths that don't start with /. For example:

• /aaa -> true, this is ok
• /aaa/bbb -> true, this is ok
• /aaa?q=x -> false, this is ok
• aaa -> true, this is NOT ok

Answer 1

The regex you've defined is a character class. Instead, try:

^\/[/.a-zA-Z0-9-]+$

Answer 2

In other words, a string that starts with /, allows alphanumeric values and doesn't allow any other special chars except these: /, ., -

You are missing some characters that are valid in URLs

import string
import urllib
import urlparse

valid_chars = string.letters + string.digits + '/.-~'
valid_paths = []

urls = ['http://www.my.uni.edu/info/matriculation/enroling.html',
    'http://info.my.org/AboutUs/Phonebook',
    'http://www.library.my.town.va.us/Catalogue/76523471236%2Fwen44--4.98',
    'http://www.my.org/462F4F2D4241522A314159265358979323846',
        'http://www.myu.edu/org/admin/people#andy',
        'http://www.w3.org/RDB/EMP?*%20where%20name%%3Ddobbins']

for i in urls:
   path = urllib.unquote(urlparse.urlparse(i).path)
   if path[0] == '/' and len([i for i in path if i in valid_chars]) == len(path):
        valid_paths.append(path)