Regex to ensure valid querystring

Question

I'm trying to come up with a Regex expression that I can use with Javascript .test to make sure my system is only accepting query strings in a valid format.

The format looks like this i=1&s1=122&s2=238&s3=167&s4=756&s5=13 It can have an unlimited number of s#= arguments in it, so could be longer or shorter than this example.

In English the format is something like i=1&s[1+0]=[any number > 0]&s[1+1]=[any number > 0]&s[1+2]=[any number > 0] and so on.

Right now the regex I have is /^([\w-]+(=[\w-]*)?(&[\w-]+(=[\w-]*)?)*)?$/ It's based on the code provided in this answer. It does an ok job of rejecting some types of invalid strings, but there are still a lot that slip through.

How can I improve this regex expression so it more accurately rejects invalid data?

s[1+2] how will regex perfomr arithmatic operations...how will it detect a linear increase in numbers? — vks
– vks, Commented Nov 14, 2014 at 6:20
If it can't that's fine. The system isn't super picky about what the keys in the key-value pairs are. I was just indicating the format in case it is possible. — Ectropy
– Ectropy, Commented Nov 14, 2014 at 6:22

Ray Toal · Accepted Answer · 2014-11-14 06:21:32Z

2

If I understand the question correctly, you can tighten things up with:

/^i=1(&s\d+=\d+)+$/

It will allow, say, s14 to come before s2, but query parameters are supposed to be unordered anyway.

answered Nov 14, 2014 at 6:21

Ray Toal

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Ectropy Over a year ago

I think this is the best one, because it correctly maintains that the string begins with i=1. I made one change, since I don't need a capturing group. Final regex expression used: ^i=1(?:&s\d+=\d+)+$

nu11p01n73R · Accepted Answer · 2014-11-14 06:21:41Z

1

How about a regex like

^i=\d+(?:&s\d+=\d+)+$

For example http://regex101.com/r/rP8vU5/2

answered Nov 14, 2014 at 6:21

nu11p01n73R

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vks · Accepted Answer · 2014-11-14 06:26:34Z

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^i=\d+(?:&s\d+=\d+(?=&|$))+$

Try this.See demo.

http://regex101.com/r/pQ9bV3/14

answered Nov 14, 2014 at 6:26

vks

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