Generate JSON directly in mysql using RAILS proof of concept

active_record_json_initializer.rb

class ActiveRecord::Base
  # Options
  # <tt>:only</tt> Only select a specific set of columns
  def self.all_as_json(options = {})

    find_columns = self.columns.collect{|x| x.name}
    find_columns = find_columns.select{|x| options[:only].include?(x)} if options[:only]

    sql_query = 'SELECT '

    sql_query += "CONCAT("

    concat_items = []
    concat_items << '"{"'

    find_columns.each_with_index do |find_column, index|
      concat_items << '"\"' + find_column + '\""'
      concat_items << '":"'
      concat_items << '"\""'
      concat_items << "`#{find_column}`"
      concat_items << '"\""'
      concat_items << '","' unless index == find_columns.length-1
    end

    concat_items << '"}"'

    sql_query += concat_items.join(',')

    sql_query += ") " # Close concat
    sql_query += "AS json "
    sql_query += "FROM `#{self.table_name}` "

    result_set = self.connection.execute(sql_query)
    result_array = []

    result_set.each_hash do |hash|
      result_array << hash['json']
    end

    "[" + result_array.join(',') + "]"
  end
end

Why do you want this? Employee.all.to_json will instantiate a heap of activerecord objects for you, only to discard discard them right after the to_json call. Please note that complex types are NOT supported :)