Convert JSON to CSV and vice-vera

csv_json.rb

require 'csv'
require 'json'
require 'active_support/all'

def json_to_csv(json_file, csv_file)
  CSV.open(csv_file, "w") do |csv|
    data = JSON.parse(File.read(json_file))
    csv << data.inject([]) { |keys, d| [keys, d.keys].flatten.uniq }.map(&:titleize)
    data.each { |d| csv << d.keys.map { |key| d[key] } }
  end
end

def csv_to_json(csv_file, json_file)
  data = []
  headers = []

  CSV.foreach(csv_file) do |row|
    if headers.empty?
      headers = row.map(&:underscore)
    else
      data.push(row.map.with_index { |value, index| [headers[index], value] }.to_h)
    end
  end

  File.open(json_file, 'w') { |f| f.write JSON.pretty_generate(data) }
end