question Re: Hi, where can i find the rules of nifi's regex language ? in Support Questions

Hi, where can i find the rules of nifi's regex language ?

thierry_vernhet — Tue, 24 May 2016 20:06:12 GMT

Re: Hi, where can i find the rules of nifi's regex language ?

pvillard — Tue, 24 May 2016 20:07:20 GMT

Hi @Thierry Vernhet

NiFi is using Java regular expressions.

Personally, I am using http://regexr.com/ to check my regular expressions.

Re: Hi, where can i find the rules of nifi's regex language ?

thierry_vernhet — Tue, 24 May 2016 20:20:03 GMT

Thanks. I'm a novice nifi's user.

I've got in a "extract text" processor this property "grok" below.

grok

^((?<year>\d+).*)$

And I don't understand exactly what it means and espacially "\d+" and ".*"

Re: Hi, where can i find the rules of nifi's regex language ?

pvillard — Tue, 24 May 2016 20:20:11 GMT

Java reference : https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

\d stands for a digit [0-9] and + means at least one digit.

.* means any characters

Re: Hi, where can i find the rules of nifi's regex language ?

andrewg — Tue, 24 May 2016 20:24:21 GMT

+1 for the RegexR - i wrote some more complex expressions with it, it has a great interactive and visual explainer to help you out as you progress. The final expression can be copied as is from there into NiFi, no special escapes needed, etc.

Re: Hi, where can i find the rules of nifi's regex language ?

andrewg — Tue, 24 May 2016 20:25:16 GMT

Check out http://regexr.com/ CheatSheet and Examples menu item on the left.

Re: Hi, where can i find the rules of nifi's regex language ?

tanmoy_official — Tue, 07 Nov 2017 18:03:50 GMT

I find nifi regex to have less options. The same regex ( [\.]conf ) in my case to find a configuration file works from outside Nifi.

But on putting this pattern in Nifi ListHDFS processor , File Pattern will not match and the file is never pulled.

Any idea why this would happen ?

Re: Hi, where can i find the rules of nifi's regex language ?

pichufr — Sun, 10 Jun 2018 02:56:40 GMT

Hi, personally I am using https://www.debuggex.com/ and https://extendsclass.com/regex-tester.html to check regex.

Re: Hi, where can i find the rules of nifi's regex language ?

baiology — Mon, 27 Aug 2018 13:16:27 GMT

Does regexr.com validates if your Nifi expression is valid as well?