Ruby script to backup iMessage transcripts.

chat-backup.rb

require 'pry'
require 'sqlite3'
require 'highline/import'

imessage_id = ask "iMessage ID (e.g., +8605555555): "
nickname = ask "Nickname (e.g., Bill): "

db = SQLite3::Database.new('/Users/ethan/Library/Messages/chat.db')

rows = db.execute "select * from message where handle_id=(
  select handle_id from chat_handle_join where chat_id=(
  select ROWID from chat where guid='iMessage;-;#{imessage_id}'))"

File.open("backup-#{imessage_id}.txt", 'w') do |file|
  file.truncate(0)

  rows.each do |row|
    sender =  if row[21] == 1
                "You"
              else
                nickname
              end

    time = Time.new(2001, 01, 01) + row[15]

    text = row[2]

    file.write("#{sender} (#{time}): #{text}\n")
  end
end