Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
tag: v3.2.9.rc2
Fetching contributors…

Cannot retrieve contributors at this time

782 lines (687 sloc) 26.336 kb
require "active_support/core_ext/module/delegation"
require "active_support/core_ext/class/attribute_accessors"
require "active_support/core_ext/array/wrap"
require 'active_support/deprecation'
module ActiveRecord
# Exception that can be raised to stop migrations from going backwards.
class IrreversibleMigration < ActiveRecordError
end
class DuplicateMigrationVersionError < ActiveRecordError#:nodoc:
def initialize(version)
super("Multiple migrations have the version number #{version}")
end
end
class DuplicateMigrationNameError < ActiveRecordError#:nodoc:
def initialize(name)
super("Multiple migrations have the name #{name}")
end
end
class UnknownMigrationVersionError < ActiveRecordError #:nodoc:
def initialize(version)
super("No migration with version number #{version}")
end
end
class IllegalMigrationNameError < ActiveRecordError#:nodoc:
def initialize(name)
super("Illegal name for migration file: #{name}\n\t(only lower case letters, numbers, and '_' allowed)")
end
end
# = Active Record Migrations
#
# Migrations can manage the evolution of a schema used by several physical
# databases. It's a solution to the common problem of adding a field to make
# a new feature work in your local database, but being unsure of how to
# push that change to other developers and to the production server. With
# migrations, you can describe the transformations in self-contained classes
# that can be checked into version control systems and executed against
# another database that might be one, two, or five versions behind.
#
# Example of a simple migration:
#
# class AddSsl < ActiveRecord::Migration
# def up
# add_column :accounts, :ssl_enabled, :boolean, :default => 1
# end
#
# def down
# remove_column :accounts, :ssl_enabled
# end
# end
#
# This migration will add a boolean flag to the accounts table and remove it
# if you're backing out of the migration. It shows how all migrations have
# two methods +up+ and +down+ that describes the transformations
# required to implement or remove the migration. These methods can consist
# of both the migration specific methods like add_column and remove_column,
# but may also contain regular Ruby code for generating data needed for the
# transformations.
#
# Example of a more complex migration that also needs to initialize data:
#
# class AddSystemSettings < ActiveRecord::Migration
# def up
# create_table :system_settings do |t|
# t.string :name
# t.string :label
# t.text :value
# t.string :type
# t.integer :position
# end
#
# SystemSetting.create :name => "notice",
# :label => "Use notice?",
# :value => 1
# end
#
# def down
# drop_table :system_settings
# end
# end
#
# This migration first adds the system_settings table, then creates the very
# first row in it using the Active Record model that relies on the table. It
# also uses the more advanced create_table syntax where you can specify a
# complete table schema in one block call.
#
# == Available transformations
#
# * <tt>create_table(name, options)</tt> Creates a table called +name+ and
# makes the table object available to a block that can then add columns to it,
# following the same format as add_column. See example above. The options hash
# is for fragments like "DEFAULT CHARSET=UTF-8" that are appended to the create
# table definition.
# * <tt>drop_table(name)</tt>: Drops the table called +name+.
# * <tt>rename_table(old_name, new_name)</tt>: Renames the table called +old_name+
# to +new_name+.
# * <tt>add_column(table_name, column_name, type, options)</tt>: Adds a new column
# to the table called +table_name+
# named +column_name+ specified to be one of the following types:
# <tt>:string</tt>, <tt>:text</tt>, <tt>:integer</tt>, <tt>:float</tt>,
# <tt>:decimal</tt>, <tt>:datetime</tt>, <tt>:timestamp</tt>, <tt>:time</tt>,
# <tt>:date</tt>, <tt>:binary</tt>, <tt>:boolean</tt>. A default value can be
# specified by passing an +options+ hash like <tt>{ :default => 11 }</tt>.
# Other options include <tt>:limit</tt> and <tt>:null</tt> (e.g.
# <tt>{ :limit => 50, :null => false }</tt>) -- see
# ActiveRecord::ConnectionAdapters::TableDefinition#column for details.
# * <tt>rename_column(table_name, column_name, new_column_name)</tt>: Renames
# a column but keeps the type and content.
# * <tt>change_column(table_name, column_name, type, options)</tt>: Changes
# the column to a different type using the same parameters as add_column.
# * <tt>remove_column(table_name, column_names)</tt>: Removes the column listed in
# +column_names+ from the table called +table_name+.
# * <tt>add_index(table_name, column_names, options)</tt>: Adds a new index
# with the name of the column. Other options include
# <tt>:name</tt>, <tt>:unique</tt> (e.g.
# <tt>{ :name => "users_name_index", :unique => true }</tt>) and <tt>:order</tt>
# (e.g. { :order => {:name => :desc} }</tt>).
# * <tt>remove_index(table_name, :column => column_name)</tt>: Removes the index
# specified by +column_name+.
# * <tt>remove_index(table_name, :name => index_name)</tt>: Removes the index
# specified by +index_name+.
#
# == Irreversible transformations
#
# Some transformations are destructive in a manner that cannot be reversed.
# Migrations of that kind should raise an <tt>ActiveRecord::IrreversibleMigration</tt>
# exception in their +down+ method.
#
# == Running migrations from within Rails
#
# The Rails package has several tools to help create and apply migrations.
#
# To generate a new migration, you can use
# rails generate migration MyNewMigration
#
# where MyNewMigration is the name of your migration. The generator will
# create an empty migration file <tt>timestamp_my_new_migration.rb</tt>
# in the <tt>db/migrate/</tt> directory where <tt>timestamp</tt> is the
# UTC formatted date and time that the migration was generated.
#
# You may then edit the <tt>up</tt> and <tt>down</tt> methods of
# MyNewMigration.
#
# There is a special syntactic shortcut to generate migrations that add fields to a table.
#
# rails generate migration add_fieldname_to_tablename fieldname:string
#
# This will generate the file <tt>timestamp_add_fieldname_to_tablename</tt>, which will look like this:
# class AddFieldnameToTablename < ActiveRecord::Migration
# def up
# add_column :tablenames, :fieldname, :string
# end
#
# def down
# remove_column :tablenames, :fieldname
# end
# end
#
# To run migrations against the currently configured database, use
# <tt>rake db:migrate</tt>. This will update the database by running all of the
# pending migrations, creating the <tt>schema_migrations</tt> table
# (see "About the schema_migrations table" section below) if missing. It will also
# invoke the db:schema:dump task, which will update your db/schema.rb file
# to match the structure of your database.
#
# To roll the database back to a previous migration version, use
# <tt>rake db:migrate VERSION=X</tt> where <tt>X</tt> is the version to which
# you wish to downgrade. If any of the migrations throw an
# <tt>ActiveRecord::IrreversibleMigration</tt> exception, that step will fail and you'll
# have some manual work to do.
#
# == Database support
#
# Migrations are currently supported in MySQL, PostgreSQL, SQLite,
# SQL Server, Sybase, and Oracle (all supported databases except DB2).
#
# == More examples
#
# Not all migrations change the schema. Some just fix the data:
#
# class RemoveEmptyTags < ActiveRecord::Migration
# def up
# Tag.all.each { |tag| tag.destroy if tag.pages.empty? }
# end
#
# def down
# # not much we can do to restore deleted data
# raise ActiveRecord::IrreversibleMigration, "Can't recover the deleted tags"
# end
# end
#
# Others remove columns when they migrate up instead of down:
#
# class RemoveUnnecessaryItemAttributes < ActiveRecord::Migration
# def up
# remove_column :items, :incomplete_items_count
# remove_column :items, :completed_items_count
# end
#
# def down
# add_column :items, :incomplete_items_count
# add_column :items, :completed_items_count
# end
# end
#
# And sometimes you need to do something in SQL not abstracted directly by migrations:
#
# class MakeJoinUnique < ActiveRecord::Migration
# def up
# execute "ALTER TABLE `pages_linked_pages` ADD UNIQUE `page_id_linked_page_id` (`page_id`,`linked_page_id`)"
# end
#
# def down
# execute "ALTER TABLE `pages_linked_pages` DROP INDEX `page_id_linked_page_id`"
# end
# end
#
# == Using a model after changing its table
#
# Sometimes you'll want to add a column in a migration and populate it
# immediately after. In that case, you'll need to make a call to
# <tt>Base#reset_column_information</tt> in order to ensure that the model has the
# latest column data from after the new column was added. Example:
#
# class AddPeopleSalary < ActiveRecord::Migration
# def up
# add_column :people, :salary, :integer
# Person.reset_column_information
# Person.all.each do |p|
# p.update_attribute :salary, SalaryCalculator.compute(p)
# end
# end
# end
#
# == Controlling verbosity
#
# By default, migrations will describe the actions they are taking, writing
# them to the console as they happen, along with benchmarks describing how
# long each step took.
#
# You can quiet them down by setting ActiveRecord::Migration.verbose = false.
#
# You can also insert your own messages and benchmarks by using the +say_with_time+
# method:
#
# def up
# ...
# say_with_time "Updating salaries..." do
# Person.all.each do |p|
# p.update_attribute :salary, SalaryCalculator.compute(p)
# end
# end
# ...
# end
#
# The phrase "Updating salaries..." would then be printed, along with the
# benchmark for the block when the block completes.
#
# == About the schema_migrations table
#
# Rails versions 2.0 and prior used to create a table called
# <tt>schema_info</tt> when using migrations. This table contained the
# version of the schema as of the last applied migration.
#
# Starting with Rails 2.1, the <tt>schema_info</tt> table is
# (automatically) replaced by the <tt>schema_migrations</tt> table, which
# contains the version numbers of all the migrations applied.
#
# As a result, it is now possible to add migration files that are numbered
# lower than the current schema version: when migrating up, those
# never-applied "interleaved" migrations will be automatically applied, and
# when migrating down, never-applied "interleaved" migrations will be skipped.
#
# == Timestamped Migrations
#
# By default, Rails generates migrations that look like:
#
# 20080717013526_your_migration_name.rb
#
# The prefix is a generation timestamp (in UTC).
#
# If you'd prefer to use numeric prefixes, you can turn timestamped migrations
# off by setting:
#
# config.active_record.timestamped_migrations = false
#
# In application.rb.
#
# == Reversible Migrations
#
# Starting with Rails 3.1, you will be able to define reversible migrations.
# Reversible migrations are migrations that know how to go +down+ for you.
# You simply supply the +up+ logic, and the Migration system will figure out
# how to execute the down commands for you.
#
# To define a reversible migration, define the +change+ method in your
# migration like this:
#
# class TenderloveMigration < ActiveRecord::Migration
# def change
# create_table(:horses) do |t|
# t.column :content, :text
# t.column :remind_at, :datetime
# end
# end
# end
#
# This migration will create the horses table for you on the way up, and
# automatically figure out how to drop the table on the way down.
#
# Some commands like +remove_column+ cannot be reversed. If you care to
# define how to move up and down in these cases, you should define the +up+
# and +down+ methods as before.
#
# If a command cannot be reversed, an
# <tt>ActiveRecord::IrreversibleMigration</tt> exception will be raised when
# the migration is moving down.
#
# For a list of commands that are reversible, please see
# <tt>ActiveRecord::Migration::CommandRecorder</tt>.
class Migration
autoload :CommandRecorder, 'active_record/migration/command_recorder'
class << self
attr_accessor :delegate # :nodoc:
end
def self.method_missing(name, *args, &block) # :nodoc:
(delegate || superclass.delegate).send(name, *args, &block)
end
def self.migrate(direction)
new.migrate direction
end
cattr_accessor :verbose
attr_accessor :name, :version
def initialize
@name = self.class.name
@version = nil
@connection = nil
@reverting = false
end
# instantiate the delegate object after initialize is defined
self.verbose = true
self.delegate = new
def revert
@reverting = true
yield
ensure
@reverting = false
end
def reverting?
@reverting
end
def up
self.class.delegate = self
return unless self.class.respond_to?(:up)
self.class.up
end
def down
self.class.delegate = self
return unless self.class.respond_to?(:down)
self.class.down
end
# Execute this migration in the named direction
def migrate(direction)
return unless respond_to?(direction)
case direction
when :up then announce "migrating"
when :down then announce "reverting"
end
time = nil
ActiveRecord::Base.connection_pool.with_connection do |conn|
@connection = conn
if respond_to?(:change)
if direction == :down
recorder = CommandRecorder.new(@connection)
suppress_messages do
@connection = recorder
change
end
@connection = conn
time = Benchmark.measure {
self.revert {
recorder.inverse.each do |cmd, args|
send(cmd, *args)
end
}
}
else
time = Benchmark.measure { change }
end
else
time = Benchmark.measure { send(direction) }
end
@connection = nil
end
case direction
when :up then announce "migrated (%.4fs)" % time.real; write
when :down then announce "reverted (%.4fs)" % time.real; write
end
end
def write(text="")
puts(text) if verbose
end
def announce(message)
text = "#{version} #{name}: #{message}"
length = [0, 75 - text.length].max
write "== %s %s" % [text, "=" * length]
end
def say(message, subitem=false)
write "#{subitem ? " ->" : "--"} #{message}"
end
def say_with_time(message)
say(message)
result = nil
time = Benchmark.measure { result = yield }
say "%.4fs" % time.real, :subitem
say("#{result} rows", :subitem) if result.is_a?(Integer)
result
end
def suppress_messages
save, self.verbose = verbose, false
yield
ensure
self.verbose = save
end
def connection
@connection || ActiveRecord::Base.connection
end
def method_missing(method, *arguments, &block)
arg_list = arguments.map{ |a| a.inspect } * ', '
say_with_time "#{method}(#{arg_list})" do
unless reverting?
unless arguments.empty? || method == :execute
arguments[0] = Migrator.proper_table_name(arguments.first)
arguments[1] = Migrator.proper_table_name(arguments.second) if method == :rename_table
end
end
return super unless connection.respond_to?(method)
connection.send(method, *arguments, &block)
end
end
def copy(destination, sources, options = {})
copied = []
FileUtils.mkdir_p(destination) unless File.exists?(destination)
destination_migrations = ActiveRecord::Migrator.migrations(destination)
last = destination_migrations.last
sources.each do |scope, path|
source_migrations = ActiveRecord::Migrator.migrations(path)
source_migrations.each do |migration|
source = File.read(migration.filename)
source = "# This migration comes from #{scope} (originally #{migration.version})\n#{source}"
if duplicate = destination_migrations.detect { |m| m.name == migration.name }
if options[:on_skip] && duplicate.scope != scope.to_s
options[:on_skip].call(scope, migration)
end
next
end
migration.version = next_migration_number(last ? last.version + 1 : 0).to_i
new_path = File.join(destination, "#{migration.version}_#{migration.name.underscore}.#{scope}.rb")
old_path, migration.filename = migration.filename, new_path
last = migration
File.open(migration.filename, "w") { |f| f.write source }
copied << migration
options[:on_copy].call(scope, migration, old_path) if options[:on_copy]
destination_migrations << migration
end
end
copied
end
def next_migration_number(number)
if ActiveRecord::Base.timestamped_migrations
[Time.now.utc.strftime("%Y%m%d%H%M%S"), "%.14d" % number].max
else
"%.3d" % number
end
end
end
# MigrationProxy is used to defer loading of the actual migration classes
# until they are needed
class MigrationProxy < Struct.new(:name, :version, :filename, :scope)
def initialize(name, version, filename, scope)
super
@migration = nil
end
def basename
File.basename(filename)
end
delegate :migrate, :announce, :write, :to => :migration
private
def migration
@migration ||= load_migration
end
def load_migration
require(File.expand_path(filename))
name.constantize.new
end
end
class Migrator#:nodoc:
class << self
attr_writer :migrations_paths
alias :migrations_path= :migrations_paths=
def migrate(migrations_paths, target_version = nil, &block)
case
when target_version.nil?
up(migrations_paths, target_version, &block)
when current_version == 0 && target_version == 0
[]
when current_version > target_version
down(migrations_paths, target_version, &block)
else
up(migrations_paths, target_version, &block)
end
end
def rollback(migrations_paths, steps=1)
move(:down, migrations_paths, steps)
end
def forward(migrations_paths, steps=1)
move(:up, migrations_paths, steps)
end
def up(migrations_paths, target_version = nil, &block)
self.new(:up, migrations_paths, target_version).migrate(&block)
end
def down(migrations_paths, target_version = nil, &block)
self.new(:down, migrations_paths, target_version).migrate(&block)
end
def run(direction, migrations_paths, target_version)
self.new(direction, migrations_paths, target_version).run
end
def schema_migrations_table_name
Base.table_name_prefix + 'schema_migrations' + Base.table_name_suffix
end
def get_all_versions
table = Arel::Table.new(schema_migrations_table_name)
Base.connection.select_values(table.project(table['version'])).map{ |v| v.to_i }.sort
end
def current_version
sm_table = schema_migrations_table_name
if Base.connection.table_exists?(sm_table)
get_all_versions.max || 0
else
0
end
end
def proper_table_name(name)
# Use the Active Record objects own table_name, or pre/suffix from ActiveRecord::Base if name is a symbol/string
name.table_name rescue "#{ActiveRecord::Base.table_name_prefix}#{name}#{ActiveRecord::Base.table_name_suffix}"
end
def migrations_paths
@migrations_paths ||= ['db/migrate']
# just to not break things if someone uses: migration_path = some_string
Array.wrap(@migrations_paths)
end
def migrations_path
migrations_paths.first
end
def migrations(paths, *args)
if args.empty?
subdirectories = true
else
subdirectories = args.first
ActiveSupport::Deprecation.warn "The `subdirectories` argument to `migrations` is deprecated"
end
paths = Array.wrap(paths)
glob = subdirectories ? "**/" : ""
files = Dir[*paths.map { |p| "#{p}/#{glob}[0-9]*_*.rb" }]
seen = Hash.new false
migrations = files.map do |file|
version, name, scope = file.scan(/([0-9]+)_([_a-z0-9]*)\.?([_a-z0-9]*)?.rb/).first
raise IllegalMigrationNameError.new(file) unless version
version = version.to_i
name = name.camelize
raise DuplicateMigrationVersionError.new(version) if seen[version]
raise DuplicateMigrationNameError.new(name) if seen[name]
seen[version] = seen[name] = true
MigrationProxy.new(name, version, file, scope)
end
migrations.sort_by(&:version)
end
private
def move(direction, migrations_paths, steps)
migrator = self.new(direction, migrations_paths)
start_index = migrator.migrations.index(migrator.current_migration)
if start_index
finish = migrator.migrations[start_index + steps]
version = finish ? finish.version : 0
send(direction, migrations_paths, version)
end
end
end
def initialize(direction, migrations_paths, target_version = nil)
raise StandardError.new("This database does not yet support migrations") unless Base.connection.supports_migrations?
Base.connection.initialize_schema_migrations_table
@direction, @migrations_paths, @target_version = direction, migrations_paths, target_version
end
def current_version
migrated.last || 0
end
def current_migration
migrations.detect { |m| m.version == current_version }
end
def run
target = migrations.detect { |m| m.version == @target_version }
raise UnknownMigrationVersionError.new(@target_version) if target.nil?
unless (up? && migrated.include?(target.version.to_i)) || (down? && !migrated.include?(target.version.to_i))
target.migrate(@direction)
record_version_state_after_migrating(target.version)
end
end
def migrate(&block)
current = migrations.detect { |m| m.version == current_version }
target = migrations.detect { |m| m.version == @target_version }
if target.nil? && @target_version && @target_version > 0
raise UnknownMigrationVersionError.new(@target_version)
end
start = up? ? 0 : (migrations.index(current) || 0)
finish = migrations.index(target) || migrations.size - 1
runnable = migrations[start..finish]
# skip the last migration if we're headed down, but not ALL the way down
runnable.pop if down? && target
ran = []
runnable.each do |migration|
if block && !block.call(migration)
next
end
Base.logger.info "Migrating to #{migration.name} (#{migration.version})" if Base.logger
seen = migrated.include?(migration.version.to_i)
# On our way up, we skip migrating the ones we've already migrated
next if up? && seen
# On our way down, we skip reverting the ones we've never migrated
if down? && !seen
migration.announce 'never migrated, skipping'; migration.write
next
end
begin
ddl_transaction do
migration.migrate(@direction)
record_version_state_after_migrating(migration.version)
end
ran << migration
rescue => e
canceled_msg = Base.connection.supports_ddl_transactions? ? "this and " : ""
raise StandardError, "An error has occurred, #{canceled_msg}all later migrations canceled:\n\n#{e}", e.backtrace
end
end
ran
end
def migrations
@migrations ||= begin
migrations = self.class.migrations(@migrations_paths)
down? ? migrations.reverse : migrations
end
end
def pending_migrations
already_migrated = migrated
migrations.reject { |m| already_migrated.include?(m.version.to_i) }
end
def migrated
@migrated_versions ||= self.class.get_all_versions
end
private
def record_version_state_after_migrating(version)
table = Arel::Table.new(self.class.schema_migrations_table_name)
@migrated_versions ||= []
if down?
@migrated_versions.delete(version)
stmt = table.where(table["version"].eq(version.to_s)).compile_delete
Base.connection.delete stmt
else
@migrated_versions.push(version).sort!
stmt = table.compile_insert table["version"] => version.to_s
Base.connection.insert stmt
end
end
def up?
@direction == :up
end
def down?
@direction == :down
end
# Wrap the migration in a transaction only if supported by the adapter.
def ddl_transaction(&block)
if Base.connection.supports_ddl_transactions?
Base.transaction { block.call }
else
block.call
end
end
end
end
Jump to Line
Something went wrong with that request. Please try again.