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NiFi - converting JSON array into Avro Map

New Contributor



On our use case, we're receiving data in JSON format and it must be converted into Avro using a schema that has X and Y includes mandatory fields and everything else (Z and W) should go into a Custom map.


Here is our Avro schema:

"fields": [
{"name": "X", "type": "long"},
{"name": "Y", "type": "string"},
{"name": "Custom", "type": { "type": "map", "values": "string" } }


And an example of data coming in:








We have implemented a JoltTransform to do the needed transformation to get Z and W into a Custom array.

Now the issue is on doing the conversion from JSON into Avro since we get an error stating it cannot convert an java.lang.Object into a Map.


How can we properly process this JSON and put that array into a Map so it can be properly stored using that Avro schema?


Thank you.

Best regards,



Master Collaborator

@migu ,


What's your NiFi version and what's your JOLT transformation?

This should work, provided that your JOLTed JSON is correct.


Please see the attached flow, which works fine for me.





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Diana Torres,
Community Moderator

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