Hi Mandeep,
I think this may actually be a bug in QueryRecord, in the way that it's
handling the Expression Language.
Do please file a JIRA for that. In the meantime, you can probably work around
the issue using the replaceNull() method.
So if your expression was ${myAttribute:jsonPath('/hello')} you could instead
use ${myAttribute:replaceNull('{}'):jsonPath('/hello')}
Thanks
-Mark
On Nov 13, 2018, at 10:16 AM, Mandeep Gill
<[email protected]<mailto:[email protected]>> wrote:
Hi there,
I'm hitting an issue using the `jsonPath` expression language function to
extract a query to use with the QueryRecord processor. The processor works fine
if the expression language subject is contained within the process group
variable registry, but fails upon starting with an
AttributeExpressionLanguageException if the subject was expected to to exist
within a flowfile attribute [1]
I've attached a template generated on NiFi 1.8.0 demonstrating the problem - it
only appears to be an issue with dynamic outputs from the QueryRecord
processors, as the same expression language statement works fine when used as
part of UpdateAttribute processor with the subject in a flowfile attribute as
per the template. I've dug into the codebase and can trace the error to the
evaluate function within the JsonPathEvaluator class, which throws the
exception if the variable can not be referenced. I have a local fix at
https://github.com/apache/nifi/compare/master...nstack:fix/jsonpath that
returns StringQueryResult("") if the subject is empty instead of throwing the
exception and this appears to work however I wonder that as UpdateAttribute
works if the problem is instead in QueryRecord eagerly evaluating the queries.
Any help would be appreciated.
Cheers,
Mandeep
[1] 2018-11-13 14:46:24,899 ERROR [Timer-Driven Process Thread-1]
o.a.nifi.processors.standard.QueryRecord
QueryRecord[id=0d5684e2-0167-1000-74c1-eb29a1401981] Failed to properly
initialize Processor. If still scheduled to run, NiFi will attempt to
initialize and run the Processor again after the 'Administrative Yield
Duration' has elapsed. Failure is due to
java.lang.reflect.InvocationTargetException:
java.lang.reflect.InvocationTargetException
java.lang.reflect.InvocationTargetException: null
at sun.reflect.GeneratedMethodAccessor916.invoke(Unknown Source)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at
org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:142)
at
org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:130)
at
org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotations(ReflectionUtils.java:75)
at
org.apache.nifi.util.ReflectionUtils.invokeMethodsWithAnnotation(ReflectionUtils.java:52)
at
org.apache.nifi.controller.StandardProcessorNode.lambda$initiateStart$4(StandardProcessorNode.java:1499)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by:
org.apache.nifi.attribute.expression.language.exception.AttributeExpressionLanguageException:
Subject is empty
at
org.apache.nifi.attribute.expression.language.evaluation.functions.JsonPathEvaluator.evaluate(JsonPathEvaluator.java:66)
at org.apache.nifi.attribute.expression.language.Query.evaluate(Query.java:315)
at
org.apache.nifi.attribute.expression.language.Query.evaluateExpression(Query.java:203)
at
org.apache.nifi.attribute.expression.language.CompiledExpression.evaluate(CompiledExpression.java:58)
at
org.apache.nifi.attribute.expression.language.StandardPreparedQuery.evaluateExpressions(StandardPreparedQuery.java:51)
at
org.apache.nifi.attribute.expression.language.StandardPropertyValue.evaluateAttributeExpressions(StandardPropertyValue.java:160)
at
org.apache.nifi.attribute.expression.language.StandardPropertyValue.evaluateAttributeExpressions(StandardPropertyValue.java:148)
at
org.apache.nifi.attribute.expression.language.StandardPropertyValue.evaluateAttributeExpressions(StandardPropertyValue.java:113)
at
org.apache.nifi.processors.standard.QueryRecord.setupQueues(QueryRecord.java:443)
... 14 common frames omitted
--
Mandeep Gill
nstack.com<http://www.nstack.com/> / +44 7961822575
<QueryRecord_JsonPath_Issue.xml>
