csvToJSON.groovy

@Grab(group = 'com.fasterxml.jackson.dataformat', module= 'jackson-dataformat-csv', version = '2.3.0')
import com.fasterxml.jackson.annotation.JsonProperty
import com.fasterxml.jackson.annotation.JsonCreator
import com.fasterxml.jackson.annotation.JsonPropertyOrder
import com.fasterxml.jackson.core.JsonFactory
import com.fasterxml.jackson.dataformat.csv.CsvMapper
import com.fasterxml.jackson.dataformat.csv.CsvSchema
import com.fasterxml.jackson.databind.MappingIterator
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.databind.ObjectWriter
import com.fasterxml.jackson.databind.SerializationFeature

USAGE = "usage: csvToGroovy.groovy source_csv_file target_json_file"
if (!args || args.length < 2) {
	println USAGE
	return
}	
csvFile = args[0]
outputFile = args[1]

CsvMapper mapper = new CsvMapper()
CsvSchema schema = CsvSchema.emptySchema().withHeader()
MappingIterator<Candle> it = mapper.reader(Candle).with(schema).readValues(new File(csvFile))
ObjectWriter ow = new ObjectMapper().writer().without(SerializationFeature.FAIL_ON_EMPTY_BEANS)									
File out = new File(outputFile)
if (out.exists()){
    out.delete()
}

while (it.hasNext()){
  row = it.next()
  out.append(ow.writeValueAsString(row))
  if (it.hasNext()) {
  	out.append("\n")
  }
}

/**
 *	POJO to hold the time series data
 */
class Candle {
	@JsonCreator
	public Candle(	@JsonProperty("date") String date,
					@JsonProperty("ticker") String ticker,
					@JsonProperty("open") String open,
					@JsonProperty("high") String high,
					@JsonProperty("low") String low,
					@JsonProperty("close") String close,
					@JsonProperty("volume") String volume) {
		this.date = date
		this.ticker = ticker
		this.open = open
		this.high = high
		this.low = low
		this.close = close
		this.volume = volume
	}

	@JsonProperty("date")
	String date
	@JsonProperty("ticker")
	String ticker
	@JsonProperty("open")
	String open
	@JsonProperty("high")
	String high
	@JsonProperty("low")
	String low
	@JsonProperty("close")
	String close
	@JsonProperty("volume") 
	String volume
}