convert json to csv in nifi

There are a few posts on this topic.  The nearest to your need with a solution is
https://community.cloudera.com/t5/Support-Questions/NiFi-JSON-Array-split/m-p/158842#M121233

The key being using the SplitJson processor the updated doc reference is 
https://nifi.apache.org/docs/nifi-docs/components/nifi-docs/components/org.apache.nifi/nifi-standard-nar/1.9.0/org.apache.nifi.processors.standard.SplitJson/index.html

This will need to be used in combination with Reader > JsonPathReader > SplitJson > Writer

Hi, @VikasNayak07 ,

An easy way to achieve this is to use a JoltTransformRecord processor with a JsonTreeReader and a CSVRecordSetWriter. The following "Chain" transformation will produce the output that you want:

[
  {
    "operation": "shift",
    "spec": {
      "tokens": {
        "*": "[&].token"
      }
    }
  }
]

Cheers,

André

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@Kiranq,

from the error message I can see that your input seems to be in avro format. Are you sure the flowfile has valid json format? If not you can use ConvertAvroToJson processor before using the jolt transformation to convert avro to json. Also from the json you provided not sure your jolt spec will work. If you provide your json input and the expected output more accurately maybe I can help you with defining the correct jolt spec.

@Kiranq,

I have to look into the JoltTranformationRecord to see what configuration you have there vs what is expected. However since you are having a json input can you use the JoltTransformationJson processor instead or are you trying to convert the output json into different format?

Can you take screenshot of the JoltTranformRecord and the reader\write services settings?

Here

JoltTransforRecord:

JsonTreeReader:

AvroReader:

Thanks.

@Kiranq,

What I found is that the JoltTransformRecord expects only single record to work with hence the name. I noticed when I try to pass an array I was getting the error "...error transforming the first record", however if I pass just one json record it works. If you have an array of json\csv and you are looking to split and process each record individually then I would suggest that you split the records before the JoltTransformRecord. If you dont want to split the array then I recommend using JoltTranformJson first and then use Convert Record processor to convert to CSV.