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From Sergei Zhirikov <>
Subject A bug in expression substitution
Date Wed, 28 Mar 2018 11:36:55 GMT
It looks like I have stumbled upon a bug in substitution of evaluated expressions.
A test case:
String result = org.apache.nifi.attribute.expression.language.Query.prepare("${foo}$${foo}").evaluateExpressions(Collections.singletonMap("foo",
"bar"), null);
Expected result: "bar${foo}"Observed result: "barbar"
The issue exists in 1.5.0 and, as far as I can tell, in the master branch.The cause is quite
simple: Query.prepare(...) splits the input string into pieces to be evaluated and substituted
or to be copied literally, but it doesn't keep track of which is which.That couldn't possibly
work. If a piece to be copied literally happens to be equal to one of the pieces to be substituted,
the things go wrong, as the test case demonstrates.


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