JSON parsing in Postgres instead of Ruby.

row_to_json.rb

ActiveRecord::Base.class_eval do
  class << self
    delegate :row_to_json, to: :all
  end
end

ActiveRecord::Relation.class_eval do
  def row_to_json
    '[' + row_to_json_result.values.join(',') + ']'
  end

  private

  def row_to_json_result
    klass.connection.execute(<<-SQL.squish)
      SELECT row_to_json(t) FROM(#{to_sql}) t
    SQL
  end
end