patch that adds two methods, dump_json and read_json to any active record model as class methods. Very useful for restoring databases onto production servers, for example.

active_record_json_dump_and_restore_monkeypatch.rb

class ActiveRecord::Base
  
  def self.dump_json(sql="")
    records = sql.blank? ? all : where(sql)
    `touch #{self}_backup.json`
    File.open(File.join(Rails.root, "#{self}_backup.json"), 'w') do |f|
      f.write(records.to_json)
    end
  end
  
  def self.read_json(safe_mode=true)
    silence do
      ids = safe_mode ? all.map(&:id) : []
      ary = JSON.parse(File.read(File.join(Rails.root, "#{self}_backup.json")))
      rcount = ary.count
      ary.each_with_index do |ar_hash, i|
        next if ids.include?(ar_hash["id"])
        print "\r#{i}/#{rcount}"
        r = new
        column_names.each do |name|
          r.send("#{name}=".to_sym, ar_hash[name])
        end
        r.save
      end# of records array
      puts "\nrecords upload complete."
    end# of silence
  end# of method
  
  def self.dump_schema
    `touch #{self}_schema_backup.json`
    File.open("#{self}_schema.json", "w") {|f| f.write(columns.map{|c| [c.name, c.type]}.to_json) }
  end#
  
end#of class