As of NiFi 1.2.0 you may be able to use ConvertRecord to do this, with a JsonTreeReader and a CSVRecordSetWriter (with a Record separator of comma and a value separator of a single space). Prior to 1.2.0 (or if the above approach doesn't work), you can use ExecuteScript. Here is a sample Groovy script that will read all the "term" values from the incoming JSON object and add an attribute called "terms" containing the comma-separated list: def flowFile = session.get()
if(!flowFile) return
def input = session.read(flowFile)
def json = new groovy.json.JsonSlurper().parse(input)
def terms = json.results.collect { it.term }.join(',')
input.close()
flowFile = session.putAttribute(flowFile, 'terms', terms)
session.transfer(flowFile, REL_SUCCESS) If instead you need to replace the content of the flow file with the comma-separated list: def flowFile = session.get()
if(!flowFile) return
flowFile = session.write(flowFile, { inputStream, outputStream ->
def json = new groovy.json.JsonSlurper().parse(inputStream)
def terms = json.results.collect { it.term }.join(',')
outputStream.write(terms.bytes)
} as StreamCallback)
flowFile = session.putAttribute(flowFile, 'mime.type', 'text/csv')
session.transfer(flowFile, REL_SUCCESS)
... View more
