csv_to_json.rb

#!/usr/bin/env ruby
require 'csv'
require 'json'
 
if ARGV.size != 2
  puts 'Usage: csv_to_json in out'
  puts
  puts '  input: Input CSV file'
  puts '  out:   Output JSON file or -- for stdout'
  puts
  puts 'This script uses the first line of the csv file as the keys for the JSON properties of the objects'
  exit(1)
end
 
lines = CSV.open(ARGV[0]).readlines
keys = lines.delete lines.first

data = lines.map do |values|
  Hash[keys.zip(values)]
end

STDOUT.reopen(File.open(ARGV[1], 'w')) unless ARGV[1].eql?('--')
puts JSON.pretty_generate(data)