no_constraint_disabling.rb

# -*- encoding : utf-8 -*-
# In order to work around the problem of the database use not having
# the permission to disable referential integrity when loading fixtures,
# we redefine disable_referential_integrity so that it doesn't try to
# disable foreign key constraints, and redefine the
# ActiveRecord::Fixtures.create_fixtures method to pay attention to the order
# which fixture tables are passed so that foreign key constraints won't be
# violated. The only lines that are changed from the initial definition
# are those between the "***" comments
require 'active_record/fixtures'
require 'active_record/connection_adapters/postgresql_adapter'
module ActiveRecord
  module ConnectionAdapters
    class PostgreSQLAdapter < AbstractAdapter
      def disable_referential_integrity(&block)
        transaction {
          yield
        }
      end
    end
  end
end

module ActiveRecord
  class Fixtures

    def self.create_fixtures(fixtures_directory, table_names, class_names = {})
      table_names = [table_names].flatten.map { |n| n.to_s }
      table_names.each { |n|
        class_names[n.tr('/', '_').to_sym] = n.classify if n.include?('/')
      }

      # FIXME: Apparently JK uses this.
      connection = block_given? ? yield : ActiveRecord::Base.connection

      files_to_read = table_names.reject { |table_name|
        fixture_is_cached?(connection, table_name)
      }

      unless files_to_read.empty?
        connection.disable_referential_integrity do
          fixtures_map = {}

          fixture_files = files_to_read.map do |path|
            table_name = path.tr '/', '_'

            fixtures_map[path] = ActiveRecord::Fixtures.new(
              connection,
              table_name,
              class_names[table_name.to_sym] || table_name.classify,
            ::File.join(fixtures_directory, path))
          end

          all_loaded_fixtures.update(fixtures_map)

          connection.transaction(:requires_new => true) do
            # Patch - replace this...
            # ***
            # fixture_files.each do |ff|
            #   conn = ff.model_class.respond_to?(:connection) ? ff.model_class.connection : connection
            #   table_rows = ff.table_rows
            #
            #   table_rows.keys.each do |table|
            #     conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
            #   end
            #
            #   table_rows.each do |table_name,rows|
            #     rows.each do |row|
            #       conn.insert_fixture(row, table_name)
            #     end
            #   end
            # end
            # ***
            # ... with this
            fixture_files.reverse.each do |ff|
              conn = ff.model_class.respond_to?(:connection) ? ff.model_class.connection : connection
              table_rows = ff.table_rows

              table_rows.keys.each do |table|
                conn.delete "DELETE FROM #{conn.quote_table_name(table)}", 'Fixture Delete'
              end
            end

            fixture_files.each do |ff|
              conn = ff.model_class.respond_to?(:connection) ? ff.model_class.connection : connection
              table_rows = ff.table_rows
              table_rows.each do |table_name,rows|
                rows.each do |row|
                  conn.insert_fixture(row, table_name)
                end
              end
            end
            # ***

            # Cap primary key sequences to max(pk).
            if connection.respond_to?(:reset_pk_sequence!)
              table_names.each do |table_name|
                connection.reset_pk_sequence!(table_name.tr('/', '_'))
              end
            end
          end

          cache_fixtures(connection, fixtures_map)
        end
      end
      cached_fixtures(connection, table_names)
    end

  end

end