NIFI-14363 - Add a replaceByPattern expression language function

[pvillard31]

Summary

NIFI-14363 - Add a replaceByPattern expression language function

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  • JDK 21

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[exceptionfactory]

Thanks for proposing this new function @pvillard31. The basic concept makes sense, but I think a different name would be more intuitive.

The mapTo name seems to imply the argument contains the destination, reminding me of the Kotlin mapTo functions. Just using map seems too generic, but something that incorporates that word is a good starting point.

Options such as mapKeyValue or mapKeyPatternValue come to mind, although the latter is more verbose. Even mapKeyValue isn't the most clear.

One other concern is the , separator, which could be problematic for matching , characters in the expression itself.

One that comes to mind is altering the approach to take only one pattern and one value at a time. This would require multiple function calls, but could be cleaner. Could the desired behavior accomplished using multiple replace or replaceFirst calls? Perhaps building on the replace naming would be a better way to go.

Those are some initial thoughts, glad to discuss this further to consider the best solution.

[pvillard31]

Thanks for the review @exceptionfactory - I pushed a commit to rename the function into replaceByPattern which seems to be a better fit.

Regarding the , separator concern, I think this is a very rare edge case where the user could use a more advanced combination of EL functions to get the desired result. An option that comes to mind is to accept an optional second argument to let the user specify the delimiter. This could be a follow up improvement if needed.

[exceptionfactory]

Thanks for making the adjustments @pvillard31. I think replaceByPattern is a good fit for the functionality, and I agree the , separator is somewhat of an edge case that could be addressed in the future with an additional optional argument providing an alternative delimiter if needed.

I plan to merge pending successful builds.

[dan-s1]

This maybe a little late but I do not think you need Collections.emptyMap() for this, couldn't you just use Map.of() ?

Suggested change

	this.compiledPatterns = compilePatterns(search.evaluate(new StandardEvaluationContext(Collections.emptyMap())).getValue());
	this.compiledPatterns = compilePatterns(search.evaluate(new StandardEvaluationContext(Map.of())).getValue());

[exceptionfactory]

Thanks @dan-s1, they are functionally equivalent, but I agree Map.of() is preferred. I just merged the PR, but good to keep in mind for the future.