CODEWITHSUNDEEP
apache-nifi
christopher_86
christopher_86

Reputation: 119

How to use Regex Capturing Group variable in NiFi Expression Language?

I am trying to replace a date format in all lines of text file using NiFi. The file looks like this:

ABCDE,20200619,23.8
FGHIJ,20200619,14.5
...

I am trying to do this using ReplaceText processor to change 20200619 to 2020-06-19. I've made regex expression matching the date ((20\d{6},)) and I have checked that it's working: when i write $1 TESTING, in Replacement value it works as expected (single line of file looks like ABCDE,20200619, TESTING,23.8).

The problem is when I try to use Expression Language and :substring function. This is my code in Replacement value:

${$1:substring(0, 4)}-${$1:substring(4, 6)}-${$1:substring(6, 8)}

But I get following error:

NiFi Error

It looks like the Expression Language can't access my $1 variable. How can I access my Regex Capturing Group variable inside Expression Language?

This is my processor:

NiFi Processor

Upvotes: 2

Views: 1997

Answers (1)

christopher_86
christopher_86

Reputation: 119

I found the answer: when trying to access Regex Capturing Group inside ${...} we need to use it with apostrophes, so the code like this works:

${'$1':substring(0, 4)}-${'$1':substring(4, 6)}-${'$1':substring(6, 8)}

Upvotes: 9

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