Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

697 lines (604 sloc) 22.872 kb
# Adds the Sequel::Migration and Sequel::Migrator classes, which allow
# the user to easily group schema changes and migrate the database
# to a newer version or revert to a previous version.
#
module Sequel
# Sequel's older migration class, available for backward compatibility.
# Uses subclasses with up and down instance methods for each migration:
#
# Class.new(Sequel::Migration) do
# def up
# create_table(:artists) do
# primary_key :id
# String :name
# end
# end
#
# def down
# drop_table(:artists)
# end
# end
#
# Part of the +migration+ extension.
class Migration
# Set the database associated with this migration.
def initialize(db)
@db = db
end
# Applies the migration to the supplied database in the specified
# direction.
def self.apply(db, direction)
raise(ArgumentError, "Invalid migration direction specified (#{direction.inspect})") unless [:up, :down].include?(direction)
new(db).send(direction)
end
# Returns the list of Migration descendants.
def self.descendants
@descendants ||= []
end
# Adds the new migration class to the list of Migration descendants.
def self.inherited(base)
descendants << base
end
# Don't allow transaction overriding in old migrations.
def self.use_transactions
nil
end
# The default down action does nothing
def down
end
# Intercepts method calls intended for the database and sends them along.
def method_missing(method_sym, *args, &block)
@db.send(method_sym, *args, &block)
end
# The default up action does nothing
def up
end
end
# Migration class used by the Sequel.migration DSL,
# using instances for each migration, unlike the
# +Migration+ class, which uses subclasses for each
# migration. Part of the +migration+ extension.
class SimpleMigration
# Proc used for the down action
attr_accessor :down
# Proc used for the up action
attr_accessor :up
# Whether to use transactions for this migration, default depends on the
# database.
attr_accessor :use_transactions
# Don't set transaction use by default.
def initialize
@use_transactions = nil
end
# Apply the appropriate block on the +Database+
# instance using instance_eval.
def apply(db, direction)
raise(ArgumentError, "Invalid migration direction specified (#{direction.inspect})") unless [:up, :down].include?(direction)
if prok = send(direction)
db.instance_eval(&prok)
end
end
end
# Internal class used by the Sequel.migration DSL, part of the +migration+ extension.
class MigrationDSL < BasicObject
# The underlying Migration instance
attr_reader :migration
def self.create(&block)
new(&block).migration
end
# Create a new migration class, and instance_eval the block.
def initialize(&block)
@migration = SimpleMigration.new
Migration.descendants << migration
instance_eval(&block)
end
# Defines the migration's down action.
def down(&block)
migration.down = block
end
# Disable the use of transactions for the related migration
def no_transaction
migration.use_transactions = false
end
# Enable the use of transactions for the related migration
def transaction
migration.use_transactions = true
end
# Defines the migration's up action.
def up(&block)
migration.up = block
end
# Creates a reversible migration. This is the same as creating
# the same block with +up+, but it also calls the block and attempts
# to create a +down+ block that will reverse the changes made by
# the block.
#
# There are no guarantees that this will work perfectly
# in all cases, but it should work for most common cases.
def change(&block)
migration.up = block
migration.down = MigrationReverser.new.reverse(&block)
end
end
# Handles the reversing of reversible migrations. Basically records
# supported methods calls, translates them to reversed calls, and
# returns them in reverse order.
class MigrationReverser < Sequel::BasicObject
def initialize
@actions = []
end
# Reverse the actions for the given block. Takes the block given
# and returns a new block that reverses the actions taken by
# the given block.
def reverse(&block)
begin
instance_eval(&block)
rescue
just_raise = true
end
if just_raise
Proc.new{raise Sequel::Error, 'irreversible migration method used, you may need to write your own down method'}
else
actions = @actions.reverse
Proc.new do
actions.each do |a|
if a.last.is_a?(Proc)
pr = a.pop
send(*a, &pr)
else
send(*a)
end
end
end
end
end
private
def add_column(*args)
@actions << [:drop_column, args[0], args[1]]
end
def add_index(*args)
@actions << [:drop_index, *args]
end
def alter_table(table, &block)
@actions << [:alter_table, table, MigrationAlterTableReverser.new.reverse(&block)]
end
def create_join_table(*args)
@actions << [:drop_join_table, *args]
end
def create_table(*args)
@actions << [:drop_table, args.first]
end
def create_view(*args)
@actions << [:drop_view, args.first]
end
def rename_column(table, name, new_name)
@actions << [:rename_column, table, new_name, name]
end
def rename_table(table, new_name)
@actions << [:rename_table, new_name, table]
end
end
# Handles reversing an alter_table block in a reversible migration.
class MigrationAlterTableReverser < Sequel::BasicObject
def initialize
@actions = []
end
def reverse(&block)
instance_eval(&block)
actions = @actions.reverse
Proc.new{actions.each{|a| send(*a)}}
end
private
def add_column(*args)
@actions << [:drop_column, args.first]
end
def add_constraint(*args)
@actions << [:drop_constraint, args.first]
end
def add_foreign_key(*args)
raise if args.first.is_a?(Array)
@actions << [:drop_column, args.first]
end
alias add_primary_key add_foreign_key
def add_index(*args)
@actions << [:drop_index, *args]
end
alias add_full_text_index add_index
alias add_spatial_index add_index
def rename_column(name, new_name)
@actions << [:rename_column, new_name, name]
end
end
# The preferred method for writing Sequel migrations, using a DSL:
#
# Sequel.migration do
# up do
# create_table(:artists) do
# primary_key :id
# String :name
# end
# end
#
# down do
# drop_table(:artists)
# end
# end
#
# Designed to be used with the +Migrator+ class, part of the +migration+ extension.
def self.migration(&block)
MigrationDSL.create(&block)
end
# The +Migrator+ class performs migrations based on migration files in a
# specified directory. The migration files should be named using the
# following pattern:
#
# <version>_<title>.rb
#
# For example, the following files are considered migration files:
#
# 001_create_sessions.rb
# 002_add_data_column.rb
#
# You can also use timestamps as version numbers:
#
# 1273253850_create_sessions.rb
# 1273257248_add_data_column.rb
#
# If any migration filenames use timestamps as version numbers, Sequel
# uses the +TimestampMigrator+ to migrate, otherwise it uses the +IntegerMigrator+.
# The +TimestampMigrator+ can handle migrations that are run out of order
# as well as migrations with the same timestamp,
# while the +IntegerMigrator+ is more strict and raises exceptions for missing
# or duplicate migration files.
#
# The migration files should contain either one +Migration+
# subclass or one <tt>Sequel.migration</tt> call.
#
# Migrations are generally run via the sequel command line tool,
# using the -m and -M switches. The -m switch specifies the migration
# directory, and the -M switch specifies the version to which to migrate.
#
# You can apply migrations using the Migrator API, as well (this is necessary
# if you want to specify the version from which to migrate in addition to the version
# to which to migrate).
# To apply a migrator, the +apply+ method must be invoked with the database
# instance, the directory of migration files and the target version. If
# no current version is supplied, it is read from the database. The migrator
# automatically creates a table (schema_info for integer migrations and
# schema_migrations for timestamped migrations). in the database to keep track
# of the current migration version. If no migration version is stored in the
# database, the version is considered to be 0. If no target version is
# specified, the database is migrated to the latest version available in the
# migration directory.
#
# For example, to migrate the database to the latest version:
#
# Sequel::Migrator.apply(DB, '.')
#
# For example, to migrate the database all the way down:
#
# Sequel::Migrator.apply(DB, '.', 0)
#
# For example, to migrate the database to version 4:
#
# Sequel::Migrator.apply(DB, '.', 4)
#
# To migrate the database from version 1 to version 5:
#
# Sequel::Migrator.apply(DB, '.', 5, 1)
#
# Part of the +migration+ extension.
class Migrator
MIGRATION_FILE_PATTERN = /\A(\d+)_.+\.rb\z/i.freeze
MIGRATION_SPLITTER = '_'.freeze
MINIMUM_TIMESTAMP = 20000101
# Exception class raised when there is an error with the migrator's
# file structure, database, or arguments.
class Error < Sequel::Error
end
# Wrapper for +run+, maintaining backwards API compatibility
def self.apply(db, directory, target = nil, current = nil)
run(db, directory, :target => target, :current => current)
end
# Migrates the supplied database using the migration files in the the specified directory. Options:
# * :column :: The column in the :table argument storing the migration version (default: :version).
# * :current :: The current version of the database. If not given, it is retrieved from the database
# using the :table and :column options.
# * :table :: The table containing the schema version (default: :schema_info).
# * :target :: The target version to which to migrate. If not given, migrates to the maximum version.
#
# Examples:
# Sequel::Migrator.run(DB, "migrations")
# Sequel::Migrator.run(DB, "migrations", :target=>15, :current=>10)
# Sequel::Migrator.run(DB, "app1/migrations", :column=> :app2_version)
# Sequel::Migrator.run(DB, "app2/migrations", :column => :app2_version, :table=>:schema_info2)
def self.run(db, directory, opts={})
migrator_class(directory).new(db, directory, opts).run
end
# Choose the Migrator subclass to use. Uses the TimestampMigrator
# if the version number appears to be a unix time integer for a year
# after 2005, otherwise uses the IntegerMigrator.
def self.migrator_class(directory)
if self.equal?(Migrator)
Dir.new(directory).each do |file|
next unless MIGRATION_FILE_PATTERN.match(file)
return TimestampMigrator if file.split(MIGRATION_SPLITTER, 2).first.to_i > MINIMUM_TIMESTAMP
end
IntegerMigrator
else
self
end
end
private_class_method :migrator_class
# The column to use to hold the migration version number for integer migrations or
# filename for timestamp migrations (defaults to :version for integer migrations and
# :filename for timestamp migrations)
attr_reader :column
# The database related to this migrator
attr_reader :db
# The directory for this migrator's files
attr_reader :directory
# The dataset for this migrator, representing the +schema_info+ table for integer
# migrations and the +schema_migrations+ table for timestamp migrations
attr_reader :ds
# All migration files in this migrator's directory
attr_reader :files
# The table to use to hold the applied migration data (defaults to :schema_info for
# integer migrations and :schema_migrations for timestamp migrations)
attr_reader :table
# The target version for this migrator
attr_reader :target
# Setup the state for the migrator
def initialize(db, directory, opts={})
raise(Error, "Must supply a valid migration path") unless File.directory?(directory)
@db = db
@directory = directory
@files = get_migration_files
schema, table = @db.send(:schema_and_table, opts[:table] || self.class.const_get(:DEFAULT_SCHEMA_TABLE))
@table = schema ? Sequel::SQL::QualifiedIdentifier.new(schema, table) : table
@column = opts[:column] || self.class.const_get(:DEFAULT_SCHEMA_COLUMN)
@ds = schema_dataset
@use_transactions = opts[:use_transactions]
end
private
# If transactions should be used for the migration, yield to the block
# inside a transaction. Otherwise, just yield to the block.
def checked_transaction(migration, &block)
use_trans = if @use_transactions.nil?
if migration.use_transactions.nil?
@db.supports_transactional_ddl?
else
migration.use_transactions
end
else
@use_transactions
end
if use_trans
db.transaction(&block)
else
yield
end
end
# Remove all migration classes. Done by the migrator to ensure that
# the correct migration classes are picked up.
def remove_migration_classes
# Remove class definitions
Migration.descendants.each do |c|
Object.send(:remove_const, c.to_s) rescue nil
end
Migration.descendants.clear # remove any defined migration classes
end
# Return the integer migration version based on the filename.
def migration_version_from_file(filename)
filename.split(MIGRATION_SPLITTER, 2).first.to_i
end
end
# The default migrator, recommended in most cases. Uses a simple incrementing
# version number starting with 1, where missing or duplicate migration file
# versions are not allowed. Part of the +migration+ extension.
class IntegerMigrator < Migrator
DEFAULT_SCHEMA_COLUMN = :version
DEFAULT_SCHEMA_TABLE = :schema_info
Error = Migrator::Error
# The current version for this migrator
attr_reader :current
# The direction of the migrator, either :up or :down
attr_reader :direction
# The migrations used by this migrator
attr_reader :migrations
# Set up all state for the migrator instance
def initialize(db, directory, opts={})
super
@target = opts[:target] || latest_migration_version
@current = opts[:current] || current_migration_version
raise(Error, "No current version available") unless current
raise(Error, "No target version available, probably because no migration files found or filenames don't follow the migration filename convention") unless target
@direction = current < target ? :up : :down
@migrations = get_migrations
end
# Apply all migrations on the database
def run
migrations.zip(version_numbers).each do |m, v|
t = Time.now
lv = up? ? v : v + 1
db.log_info("Begin applying migration version #{lv}, direction: #{direction}")
checked_transaction(m) do
m.apply(db, direction)
set_migration_version(v)
end
db.log_info("Finished applying migration version #{lv}, direction: #{direction}, took #{sprintf('%0.6f', Time.now - t)} seconds")
end
target
end
private
# Gets the current migration version stored in the database. If no version
# number is stored, 0 is returned.
def current_migration_version
ds.get(column) || 0
end
# Returns any found migration files in the supplied directory.
def get_migration_files
files = []
Dir.new(directory).each do |file|
next unless MIGRATION_FILE_PATTERN.match(file)
version = migration_version_from_file(file)
if version >= 20000101
raise Migrator::Error, "Migration number too large, must use TimestampMigrator: #{file}"
end
raise(Error, "Duplicate migration version: #{version}") if files[version]
files[version] = File.join(directory, file)
end
1.upto(files.length - 1){|i| raise(Error, "Missing migration version: #{i}") unless files[i]}
files
end
# Returns a list of migration classes filtered for the migration range and
# ordered according to the migration direction.
def get_migrations
remove_migration_classes
# load migration files
files[up? ? (current + 1)..target : (target + 1)..current].compact.each{|f| load(f)}
# get migration classes
classes = Migration.descendants
up? ? classes : classes.reverse
end
# Returns the latest version available in the specified directory.
def latest_migration_version
l = files.last
l ? migration_version_from_file(File.basename(l)) : nil
end
# Returns the dataset for the schema_info table. If no such table
# exists, it is automatically created.
def schema_dataset
c = column
ds = db.from(table)
if !db.table_exists?(table)
db.create_table(table){Integer c, :default=>0, :null=>false}
elsif !ds.columns.include?(c)
db.alter_table(table){add_column c, Integer, :default=>0, :null=>false}
end
ds.insert(c=>0) if ds.empty?
raise(Error, "More than 1 row in migrator table") if ds.count > 1
ds
end
# Sets the current migration version stored in the database.
def set_migration_version(version)
ds.update(column=>version)
end
# Whether or not this is an up migration
def up?
direction == :up
end
# An array of numbers corresponding to the migrations,
# so that each number in the array is the migration version
# that will be in affect after the migration is run.
def version_numbers
up? ? ((current+1)..target).to_a : (target..(current - 1)).to_a.reverse
end
end
# The migrator used if any migration file version appears to be a timestamp.
# Stores filenames of migration files, and can figure out which migrations
# have not been applied and apply them, even if earlier migrations are added
# after later migrations. If you plan to do that, the responsibility is on
# you to make sure the migrations don't conflict. Part of the +migration+ extension.
class TimestampMigrator < Migrator
DEFAULT_SCHEMA_COLUMN = :filename
DEFAULT_SCHEMA_TABLE = :schema_migrations
Error = Migrator::Error
# Array of strings of applied migration filenames
attr_reader :applied_migrations
# Get tuples of migrations, filenames, and actions for each migration
attr_reader :migration_tuples
# Set up all state for the migrator instance
def initialize(db, directory, opts={})
super
@target = opts[:target]
@applied_migrations = get_applied_migrations
@migration_tuples = get_migration_tuples
end
# Apply all migration tuples on the database
def run
migration_tuples.each do |m, f, direction|
t = Time.now
db.log_info("Begin applying migration #{f}, direction: #{direction}")
checked_transaction(m) do
m.apply(db, direction)
fi = f.downcase
direction == :up ? ds.insert(column=>fi) : ds.filter(column=>fi).delete
end
db.log_info("Finished applying migration #{f}, direction: #{direction}, took #{sprintf('%0.6f', Time.now - t)} seconds")
end
nil
end
private
# Convert the schema_info table to the new schema_migrations table format,
# using the version of the schema_info table and the current migration files.
def convert_from_schema_info
v = db[IntegerMigrator::DEFAULT_SCHEMA_TABLE].get(IntegerMigrator::DEFAULT_SCHEMA_COLUMN)
ds = db.from(table)
files.each do |path|
f = File.basename(path)
if migration_version_from_file(f) <= v
ds.insert(column=>f)
end
end
end
# Returns filenames of all applied migrations
def get_applied_migrations
am = ds.select_order_map(column)
missing_migration_files = am - files.map{|f| File.basename(f).downcase}
raise(Error, "Applied migration files not in file system: #{missing_migration_files.join(', ')}") if missing_migration_files.length > 0
am
end
# Returns any migration files found in the migrator's directory.
def get_migration_files
files = []
Dir.new(directory).each do |file|
next unless MIGRATION_FILE_PATTERN.match(file)
files << File.join(directory, file)
end
files.sort_by{|f| MIGRATION_FILE_PATTERN.match(File.basename(f))[1].to_i}
end
# Returns tuples of migration, filename, and direction
def get_migration_tuples
remove_migration_classes
up_mts = []
down_mts = []
ms = Migration.descendants
files.each do |path|
f = File.basename(path)
fi = f.downcase
if target
if migration_version_from_file(f) > target
if applied_migrations.include?(fi)
load(path)
down_mts << [ms.last, f, :down]
end
elsif !applied_migrations.include?(fi)
load(path)
up_mts << [ms.last, f, :up]
end
elsif !applied_migrations.include?(fi)
load(path)
up_mts << [ms.last, f, :up]
end
end
up_mts + down_mts.reverse
end
# Returns the dataset for the schema_migrations table. If no such table
# exists, it is automatically created.
def schema_dataset
c = column
ds = db.from(table)
if !db.table_exists?(table)
db.create_table(table){String c, :primary_key=>true}
if db.table_exists?(:schema_info) and vha = db[:schema_info].all and vha.length == 1 and
vha.first.keys == [:version] and vha.first.values.first.is_a?(Integer)
convert_from_schema_info
end
elsif !ds.columns.include?(c)
raise(Error, "Migrator table #{table} does not contain column #{c}")
end
ds
end
end
end
Jump to Line
Something went wrong with that request. Please try again.