[jira] [Created] (NIFI-5026) Expression Language Query.prepare function can sometimes ignore escape sequence

[Mark Payne (JIRA)]

Mark Payne created NIFI-5026:
--------------------------------

             Summary: Expression Language Query.prepare function can sometimes 
ignore escape sequence
                 Key: NIFI-5026
                 URL: https://issues.apache.org/jira/browse/NIFI-5026
             Project: Apache NiFi
          Issue Type: Bug
          Components: Core Framework
            Reporter: Mark Payne
            Assignee: Mark Payne


As reported on the [dev@n.a.o|mailto:dev@n.a.o] mailing list:

 

Hi,
It looks like I have stumbled upon a bug in substitution of evaluated 
expressions.
A test case:
{code:java}
String result = 
org.apache.nifi.attribute.expression.language.Query.prepare("${foo}$${foo}").evaluateExpressions(Collections.singletonMap("foo",
 "bar"), null);{code}

Expected result:
{code:java}
bar${foo}{code}
Observed result:
{code:java}
barbar{code}

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.

 



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