csv_to_json.rb

#!/usr/bin/env ruby
require 'csv'
require 'json'

if ARGV.size != 2
  puts 'Usage: csv_to_json input_file.csv output_file.json'
  puts 'This script uses the first line of the csv file as the keys for the JSON properties of the objects'
  exit(1)
end

extracted_data   = CSV.table(ARGV[0])
transformed_data = extracted_data.map { |row| row.to_hash }

File.open(ARGV[1], 'w') do |file|
  file.puts JSON.pretty_generate(transformed_data)
end