Reads from STDIN or a file, converts \G mysql formatted results to csv, and writes to STDOUT

mysql-to-csv.rb

require "csv"

# Reads from STDIN or a file, converts \G mysql formatted results to csv, and writes to STDOUT
#
# STDIN Usage:
#   mysql ... | ruby mysql-to-csv.rb
# 
# File Usage:
#   ruby mysql-to-csv.rb results.txt
#
# Example Format: 
#   *************************** 452. row ***************************
#      column_one: 1
#      column_two: 123744
#    column_three: 0

ROW_MARKER = /^\*+ \d+\. row \*+$/
KEY_VALUE_PAIR = /^\s*(?<key>[^:]+): (?<value>.*)$/

CSV do |csv|  
  first_row = true
  headers = []
  row = nil
  ARGF.readlines.each do |line|
    line.chomp!
  
    if ROW_MARKER === line
      if !headers.empty? && first_row
        csv << headers 
        first_row = false
      end
      csv << row if row
      row = []
      next
    end
    
    if match_data = line.match(KEY_VALUE_PAIR)
      headers << match_data[:key] if first_row
      row << match_data[:value]
      next
    end
  end
end