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https://issues.apache.org/jira/browse/NIFI-1249?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15042280#comment-15042280
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ASF subversion and git services commented on NIFI-1249:
-------------------------------------------------------
Commit f378ee902127bd29b168c9bb15e991abe4eab0fa in nifi's branch
refs/heads/master from [~markap14]
[ https://git-wip-us.apache.org/repos/asf?p=nifi.git;h=f378ee9 ]
NIFI-1249: Allow Processors to add their own variables to those referencable by
Expression Language. Make ReplaceText allow users to reference back-references
of regex matches
> Allow ReplaceText expression language functions to access matching group
> values
> -------------------------------------------------------------------------------
>
> Key: NIFI-1249
> URL: https://issues.apache.org/jira/browse/NIFI-1249
> Project: Apache NiFi
> Issue Type: Improvement
> Components: Extensions
> Reporter: Joseph Witt
> Assignee: Mark Payne
> Fix For: 0.4.0
>
> Attachments:
> 0001-NIFI-1249-Allow-Processors-to-add-their-own-variable.patch, NIFI-1249.xml
>
>
> Chanru from the user's mailing list asked how we'd support a pretty simple
> use case of converting
> {quote}
> col1,col2,col3
> 2006,10-01-2004,10may2004
> 2007,15-05-2006,10jun2005
> 2009,8-8-2008,10aug2008
> {quote}
> to this
> {quote}
> col1,col2,col3
> 2006,10-01-2004,2004-05-10
> 2007,15-05-2006,2005-06-10
> 2009,8-8-2008,2008-08-10
> {quote}
> And we can do it today but it is surprising more effort than it should be.
> The problem is that ReplaceText as-is gets us sooo close. But what it cannot
> do is convert the original column three into a formatted Date object which
> can then be written out as a formatted string. If it could then this would
> be easy. So for example if we extracted each column as a matching group and
> the replacement value could be
> {code}
> ${ $3:toDate('ddMMMyyy'):format('yyyy/MM/ddd')}
> {code}
> Then we'd be all set. But right now there is no way to take that third
> matching group and do anything fun with expression language on it because it
> is not a subject passed into the EL on which functions could be applied. If
> instead we simply added those matching groups as keys/subjects available to
> the EL then this becomes a quite powerful tool.
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