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

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.6.0
• Component/s: Core Framework
• Assignee: Mark Payne
• Reporter: Mark Payne
• Created: 28/Mar/18 16:41
• Updated: 02/Apr/18 15:25
• Resolved: 29/Mar/18 08:54

Description

As reported on the dev@n.a.o mailing list:

 

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.

 

Issue Links

• links to: GitHub Pull Request #2592