Apache NiFi : QueryRecord JSON Select child field

Question

Is it possible to select with the QueryRecord processor also child fields of an given JSON structrue?

E.g. following JSON:

{
  "name" : "Max",
  "id" : 1,
  "location" : {
    "city" : "Frankfurt"
  }
}

And I would do the following query:

SELECT name, location.city FROM FLOWFILE

But this throws an error:

QueryRecord[id=a4744340-017a-1000-6944-73fe4d362d90] Unable to query StandardFlowFileRecord[uuid=706e8ae8-f76c-4ebb-9c65-c46cb7026c89,claim=StandardContentClaim [resourceClaim=StandardResourceClaim[id=1626251405764-2, container=default, section=2], offset=790026, length=67],offset=0,name=55b72cfd-5308-4e83-9304-166193e76478,size=67] due to java.sql.SQLException: Error while preparing statement [SELECT "name", "location.city" FROM FLOWFILE]: org.apache.nifi.processor.exception.ProcessException: java.sql.SQLException: Error while preparing statement [SELECT "name", "location.city" FROM FLOWFILE]

Is there something that I'm doing wrong? Here is the configuration:

mkohs · Accepted Answer

Hi @janis-ax ,

This reply comes a bit late but I was just researching the same issue. According to the official NiFi documentation, this should be possible using the "RPath" function in the 'Where' clause.

Check out the "SQL over hierarchical data" section here: https://nifi.apache.org/docs/nifi-docs/components/org.apache.nifi/nifi-standard-nar/latest/org.apache.nifi.processors.standard.QueryRecord/additionalDetails.html

araujo · Answer

As @mkohs mentioned, using the RPATH function is the way to go here.

It can be used on the SELECT clause, for projection, as well as on the WHERE cause, for filtering.

You can see a similar use of it in this post here: https://community.cloudera.com/t5/Support-Questions/QueryRecord-processor-issue-with-nested-JSON/td-p/338556

Cheers,

André

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