+++ /dev/null
-module ActiveRecord
- class IrreversibleMigration < ActiveRecordError#:nodoc:
- 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
-
- # 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 self.up
- # add_column :accounts, :ssl_enabled, :boolean, :default => 1
- # end
- #
- # def self.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 class 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 self.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 self.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_name)</tt>: Removes the column named +column_name+ 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> and <tt>:unique</tt> (e.g. <tt>{ :name => "users_name_index", :unique => true }</tt>).
- # * <tt>remove_index(table_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
- # script/generate migration MyNewMigration
- #
- # where MyNewMigration is the name of your migration. The generator will
- # create an empty migration file <tt>nnn_my_new_migration.rb</tt> in the <tt>db/migrate/</tt>
- # directory where <tt>nnn</tt> is the next largest migration number.
- #
- # You may then edit the <tt>self.up</tt> and <tt>self.down</tt> methods of
- # MyNewMigration.
- #
- # There is a special syntactic shortcut to generate migrations that add fields to a table.
- # script/generate migration add_fieldname_to_tablename fieldname:string
- #
- # This will generate the file <tt>nnn_add_fieldname_to_tablename</tt>, which will look like this:
- # class AddFieldnameToTablename < ActiveRecord::Migration
- # def self.up
- # add_column :tablenames, :fieldname, :string
- # end
- #
- # def self.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 self.up
- # Tag.find(:all).each { |tag| tag.destroy if tag.pages.empty? }
- # end
- #
- # def self.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 self.up
- # remove_column :items, :incomplete_items_count
- # remove_column :items, :completed_items_count
- # end
- #
- # def self.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 self.up
- # execute "ALTER TABLE `pages_linked_pages` ADD UNIQUE `page_id_linked_page_id` (`page_id`,`linked_page_id`)"
- # end
- #
- # def self.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 Base#reset_column_information 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 self.up
- # add_column :people, :salary, :integer
- # Person.reset_column_information
- # Person.find(: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 self.up
- # ...
- # say_with_time "Updating salaries..." do
- # Person.find(: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 environment.rb.
- #
- class Migration
- @@verbose = true
- cattr_accessor :verbose
-
- class << self
- def up_with_benchmarks #:nodoc:
- migrate(:up)
- end
-
- def down_with_benchmarks #:nodoc:
- migrate(: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
-
- result = nil
- time = Benchmark.measure { result = send("#{direction}_without_benchmarks") }
-
- case direction
- when :up then announce "migrated (%.4fs)" % time.real; write
- when :down then announce "reverted (%.4fs)" % time.real; write
- end
-
- result
- end
-
- # Because the method added may do an alias_method, it can be invoked
- # recursively. We use @ignore_new_methods as a guard to indicate whether
- # it is safe for the call to proceed.
- def singleton_method_added(sym) #:nodoc:
- return if defined?(@ignore_new_methods) && @ignore_new_methods
-
- begin
- @ignore_new_methods = true
-
- case sym
- when :up, :down
- klass = (class << self; self; end)
- klass.send(:alias_method_chain, sym, "benchmarks")
- end
- ensure
- @ignore_new_methods = false
- 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
- ActiveRecord::Base.connection
- end
-
- def method_missing(method, *arguments, &block)
- arg_list = arguments.map(&:inspect) * ', '
-
- say_with_time "#{method}(#{arg_list})" do
- unless arguments.empty? || method == :execute
- arguments[0] = Migrator.proper_table_name(arguments.first)
- end
- connection.send(method, *arguments, &block)
- end
- end
- end
- end
-
- # MigrationProxy is used to defer loading of the actual migration classes
- # until they are needed
- class MigrationProxy
-
- attr_accessor :name, :version, :filename
-
- delegate :migrate, :announce, :write, :to=>:migration
-
- private
-
- def migration
- @migration ||= load_migration
- end
-
- def load_migration
- load(filename)
- name.constantize
- end
-
- end
-
- class Migrator#:nodoc:
- class << self
- def migrate(migrations_path, target_version = nil)
- case
- when target_version.nil? then up(migrations_path, target_version)
- when current_version > target_version then down(migrations_path, target_version)
- else up(migrations_path, target_version)
- end
- end
-
- def rollback(migrations_path, steps=1)
- migrator = self.new(:down, migrations_path)
- start_index = migrator.migrations.index(migrator.current_migration)
-
- return unless start_index
-
- finish = migrator.migrations[start_index + steps]
- down(migrations_path, finish ? finish.version : 0)
- end
-
- def up(migrations_path, target_version = nil)
- self.new(:up, migrations_path, target_version).migrate
- end
-
- def down(migrations_path, target_version = nil)
- self.new(:down, migrations_path, target_version).migrate
- end
-
- def run(direction, migrations_path, target_version)
- self.new(direction, migrations_path, target_version).run
- end
-
- def schema_migrations_table_name
- Base.table_name_prefix + 'schema_migrations' + Base.table_name_suffix
- end
-
- def get_all_versions
- Base.connection.select_values("SELECT version FROM #{schema_migrations_table_name}").map(&: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
- end
-
- def initialize(direction, migrations_path, 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_path, @target_version = direction, migrations_path, 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
- current = migrations.detect { |m| m.version == current_version }
- target = migrations.detect { |m| m.version == @target_version }
-
- if target.nil? && !@target_version.nil? && @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.nil?
-
- runnable.each do |migration|
- Base.logger.info "Migrating to #{migration.name} (#{migration.version})"
-
- # On our way up, we skip migrating the ones we've already migrated
- next if up? && migrated.include?(migration.version.to_i)
-
- # On our way down, we skip reverting the ones we've never migrated
- if down? && !migrated.include?(migration.version.to_i)
- migration.announce 'never migrated, skipping'; migration.write
- next
- end
-
- begin
- ddl_transaction do
- migration.migrate(@direction)
- record_version_state_after_migrating(migration.version)
- end
- 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
- end
-
- def migrations
- @migrations ||= begin
- files = Dir["#{@migrations_path}/[0-9]*_*.rb"]
-
- migrations = files.inject([]) do |klasses, file|
- version, name = file.scan(/([0-9]+)_([_a-z0-9]*).rb/).first
-
- raise IllegalMigrationNameError.new(file) unless version
- version = version.to_i
-
- if klasses.detect { |m| m.version == version }
- raise DuplicateMigrationVersionError.new(version)
- end
-
- if klasses.detect { |m| m.name == name.camelize }
- raise DuplicateMigrationNameError.new(name.camelize)
- end
-
- klasses << returning(MigrationProxy.new) do |migration|
- migration.name = name.camelize
- migration.version = version
- migration.filename = file
- end
- end
-
- migrations = migrations.sort_by(&:version)
- 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)
- sm_table = self.class.schema_migrations_table_name
-
- @migrated_versions ||= []
- if down?
- @migrated_versions.delete(version.to_i)
- Base.connection.update("DELETE FROM #{sm_table} WHERE version = '#{version}'")
- else
- @migrated_versions.push(version.to_i).sort!
- Base.connection.insert("INSERT INTO #{sm_table} (version) VALUES ('#{version}')")
- 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
projects / feedcatcher.git / blobdiff