Hi,
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.
Regards,Sergei.
