Extracting a value from query string using Regex

Question

I'm trying to extract the value from this string using regex but I can't seem to get it right.

string:

?Ntt=crockett%20&%20Jones&Rdm=718&searchType=simple&type=search&Ns=&N=&Nrpp=12&No=0&Nr=AND(product.active:1,NOT(record.type:Store))

I need the value of Ntt which is crockett%20&%20Jones.

The regex I have currently is:

\?Ntt=(([&%])|([^&=]))*

but this results in:

?Ntt=crockett%20&%20Jones&Rdm

How can I update my regex to produce the value I need?

the & usually separates inputs in a query string. Are you sure you need &%20Jones? IF not, use [&\?]Ntt=([^&]*) — mankowitz
– mankowitz, Commented Dec 22, 2020 at 11:28
@mankowitz, I do need &%20Jones - that's why I'm struggling to find a suitable regex — Akshay Rajpaul
– Akshay Rajpaul, Commented Dec 22, 2020 at 11:35
How do you know that the second group is part of what you are trying to capture? In other words, how do you know how much you need? — mankowitz
– mankowitz, Commented Dec 22, 2020 at 11:41

Wiktor Stribiżew · Accepted Answer · 2020-12-22 11:35:47Z

1

You can use a capturing group based regex like

[&?]Ntt=((?:%20&%20|[^&])*)

Alternatively, you can use a lookbehind based regex like

(?<=[&?]Ntt=)(?:%20&%20|[^&])*

Details

(?<=[&?]Ntt=) - a positive lookbehind that matches a location that is immediately preceded with ? or & and then Ntt=
(?:%20&%20|[^&])* - a non-capturing group that matches zero or more occurrences of a %20&%20 substring or any char other than &.

answered Dec 22, 2020 at 11:35

Wiktor Stribiżew

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Comments

mankowitz · Accepted Answer · 2020-12-22 11:39:15Z

0

[&\?]Ntt=([^&]*)

First capture the separator (either ? or &), then capture the key, then capture everything until the next separator.

answered Dec 22, 2020 at 11:39

mankowitz

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