Script to convert JSON array to CSV rows

json_to_csv.rb

require 'json'
require 'csv'

# ruby json_to_csv.rb /path/to/data.json > /path/to/data.csv
#
MAP_VALUE = ->(value) {
  case value
  when Array
    value.join('|')
  when Hash
    value.to_json
  else
    value
  end
}

path = ARGV[0] || raise('Please provide a path to a CSV file')

data = JSON.parse(File.read(path))

headers = data.first&.keys
puts 'no data' and exit if headers.nil?

puts (CSV.generate do |csv|
  csv << headers
  data.each do |row|
    r = headers.map { |h| MAP_VALUE.(row[h]) }
    csv << r
  end
end)