Re: Content replacement

Fri, 04 Dec 2015 14:06:06 -0800

Chandru,

This ticket has now been merged to master. This feature will be available in 0.4.0, which should be out next week. If you
prefer to build from source, it is now available for use from master. You should be able to now configure ReplaceText to
easily replace the values:



Here, we use the Search value of (.*?),(.*?),(\d+.*)
So the first Capturing Group gets the first column, the second Capturing Group gets the second column, and the third Capturing Group gets the third column (but only if it starts with a digit, so this won't match the header line and the header line will remain unchanged).

For the Replacement Value, we use: $1,$2,${ '$3':toDate( 'ddMMMyyyy'):format('yyyy/MM/dd') }
So here we are using back references to replace the line with the first two columns, followed by an _expression_ Language _expression_ that parses the third back reference (the third column).
Since the variable that we want to reference is named $3, we need to enclose it in quotes to escape the name because it begins with a non-alpha character. We can then call any _expression_ Language
_expression_ that we want. So toDate() can be used to parse the string as Date and then we can use format() to format that date as a string in a different format.

You can also see the template available on the NIFI-1249 ticket, also attached for convenience here, but I don't know if the apache mailing list will let the template through.

This was a great addition to NiFi that I think will help out in a lot of cases - thanks for reaching out to us on this! 
Please let us know if you have issues getting this to work, or if you have any further questions. We're happy to help however we can.

Thanks
-Mark


Attachment: NIFI-1249.xml
Description: XML document




On Dec 4, 2015, at 3:44 PM, Joe Witt <[email protected]> wrote:

Chandru,

Correct what you're trying doesn't work just yet.  But once this [1] is reviewed and pushed to master we should have your original request covered quite nicely.


Thanks
Joe 

On Fri, Dec 4, 2015 at 3:26 PM, Chandu Koripella <[email protected]> wrote:

Thanks Joe,

 

I believe I tried this option earlier. As you notice I have 4 groups in the regular _expression_. I tried with all four groups. Nothing gets replaced in the put file.

 

Group4 is 4 digit year, group3 is 3 digit month, group2 is date and group1 is ddMMMyyyy

 

 

<image001.png>

 

From: Joe Witt [mailto:[email protected]]
Sent: Thursday, December 03, 2015 7:00 PM
To: [email protected]
Subject: Re: Content replacement

 

Your use case description was excellent and helped expose a powerful and simple feature enhancement.

 

 

Thanks

Joe

 

On Thu, Dec 3, 2015 at 9:21 PM, Joe Witt <[email protected]> wrote:

Chandu,

 

In building a template to support this I'm finding it more involved than desired.  If I get that done will post it unless someone else does so sooner.  However, the only reason it is more involved than I'd like is that the ReplaceText processor does almost everything we need here.  It can be in line mode to do the eval/replace on a per line basis and it can extract groups from the matching line and use those groups to format a new output.  However, the difficulty in your example is that we cannot take that date string and convert it to a date and then format it back to a string (right now).  So will take a look at how we could better support the use case as well.

 

Something else of note is that there are a couple of folks working on scripting processors so you could break into a convenient script to help tackle some cases like this as well.

 

Will dig a bit more and respond.

 

Thanks

Joe

 

On Thu, Dec 3, 2015 at 8:20 PM, Chandu Koripella <[email protected]> wrote:

HI,

 

I am very new to the nifi and evaluating to use to do simple transformations. I am trying to convert date format from ddMMMyyyy to  yyyy/mm/dd using replace text option. I don’t find many options to do content replacement in the documentation. it is more focused for attribute manipulation.

 

 

<image004.png>

Hsere is my simple file format. how do I transform the data in col3? I appricaiate any help.

 

<image005.png>

 

Thanks,

Chandu

 

 



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