How to extract avoiding special characters using regular expression extractor in Jmeter

Question

I am trying to extract XYZ from the below :

checkboxes__input' id='XYZ_2020-04-20' name='payment[invoices][XYZ][]' type='checkbox' value='2020-04-20'

using regular expression:

name='payment[invoices][(.*?)][]' type=

but it does not work. Can anyone please help me with this?

Answer 1

As per JMeter Regular Expressions guide [ and ] are meta characters which stand for character classes therefore they need to be escaped with a backslash like:

name='payment\[invoices\]\[(.*?)\]\[\]' type=

Demo:

---

If you're not too comfortable with regular expressions you can consider switching to the Boundary Extractor where you can just provide left and right boundaries and it will extract everything between them: