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Class: ActiveRecord::Migrator

Do not use. This class is for internal use only.
Relationships & Source Files
Inherits: Object
Defined in: activerecord/lib/active_record/migration.rb

Constant Summary

Class Attribute Summary

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(direction, migrations, schema_migration, internal_metadata, target_version = nil) ⇒ Migrator

[ GitHub ] 

  


# File 'activerecord/lib/active_record/migration.rb', line 1421



def initialize(direction, migrations, schema_migration, internal_metadata, target_version = nil)
  @direction         = direction
  @target_version    = target_version
  @migrated_versions = nil
  @migrations        = migrations
  @schema_migration  = schema_migration
  @internal_metadata = internal_metadata

  validate(@migrations)

  @schema_migration.create_table
  @internal_metadata.create_table
end


  







Class Attribute Details



  

    .migrations_paths   (rw)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1407



attr_accessor :migrations_paths


  







Class Method Details



  

    .current_version  
  



  

    

For cases where a table doesn’t exist like loading from schema cache


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1410



def current_version
  connection_pool = ActiveRecord::Tasks::DatabaseTasks.migration_connection_pool
  schema_migration = SchemaMigration.new(connection_pool)
  internal_metadata = InternalMetadata.new(connection_pool)

  MigrationContext.new(migrations_paths, schema_migration, internal_metadata).current_version
end


  







Instance Attribute Details



  

    #down?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1579



def down?
  @direction == :down
end


  








  

    #invalid_target?  ⇒ Boolean  (readonly, private)
  



  

    

Return true if a valid version is not provided.


  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1524



def invalid_target?
  @target_version && @target_version != 0 && !target
end


  








  

    #up?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1575



def up?
  @direction == :up
end


  








  

    #use_advisory_lock?  ⇒ Boolean  (readonly, private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1596



def use_advisory_lock?
  connection.advisory_locks_enabled?
end


  







Instance Method Details



  

    #connection   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1489



def connection
  ActiveRecord::Tasks::DatabaseTasks.migration_connection
end


  








  

    #current  
  



  

    

Alias for #current_migration.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1442



alias :current :current_migration


  








  

    #current_migration  
    Also known as: #current
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1439



def current_migration
  migrations.detect { |m| m.version == current_version }
end


  








  

    #current_version  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1435



def current_version
  migrated.max || 0
end


  








  

    #ddl_transaction(migration, &block)   (private)
  



  

    

Wrap the migration in a transaction only if supported by the adapter.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1584



def ddl_transaction(migration, &block)
  if use_transaction?(migration)
    connection.transaction(&block)
  else
    yield
  end
end


  








  

    #execute_migration_in_transaction(migration)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1528



def execute_migration_in_transaction(migration)
  return if down? && !migrated.include?(migration.version.to_i)
  return if up?   &&  migrated.include?(migration.version.to_i)

  Base.logger.info "Migrating to #{migration.name} (#{migration.version})" if Base.logger

  ddl_transaction(migration) do
    migration.migrate(@direction)
    record_version_state_after_migrating(migration.version)
  end
rescue => e
  msg = +"An error has occurred, "
  msg << "this and " if use_transaction?(migration)
  msg << "all later migrations canceled:\n\n#{e}"
  raise StandardError, msg, e.backtrace
end


  








  

    #finish   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1549



def finish
  migrations.index(target) || migrations.size - 1
end


  








  

    #generate_migrator_advisory_lock_id   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1616



def generate_migrator_advisory_lock_id
  db_name_hash = Zlib.crc32(connection.current_database)
  MIGRATOR_SALT * db_name_hash
end


  








  

    #load_migrated  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1484



def load_migrated
  @migrated_versions = Set.new(@schema_migration.integer_versions)
end


  








  

    #migrate  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1452



def migrate
  if use_advisory_lock?
    with_advisory_lock { migrate_without_lock }
  else
    migrate_without_lock
  end
end


  








  

    #migrate_without_lock   (private)
  



  

    

Used for running multiple migrations up to or down to a certain value.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1503



def migrate_without_lock
  if invalid_target?
    raise UnknownMigrationVersionError.new(@target_version)
  end

  record_environment
  runnable.each(&method(:execute_migration_in_transaction))
end


  








  

    #migrated  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1480



def migrated
  @migrated_versions || load_migrated
end


  








  

    #migrations  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1471



def migrations
  down? ? @migrations.reverse : @migrations.sort_by(&:version)
end


  








  

    #pending_migrations  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1475



def pending_migrations
  already_migrated = migrated
  migrations.reject { |m| already_migrated.include?(m.version) }
end


  








  

    #ran?(migration)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1519



def ran?(migration)
  migrated.include?(migration.version.to_i)
end


  








  

    #record_environment   (private)
  



  

    

Stores the current environment in the database.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1513



def record_environment
  return if down?

  @internal_metadata[:environment] = connection.pool.db_config.env_name
end


  








  

    #record_version_state_after_migrating(version)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1565



def record_version_state_after_migrating(version)
  if down?
    migrated.delete(version)
    @schema_migration.delete_version(version.to_s)
  else
    migrated << version
    @schema_migration.create_version(version.to_s)
  end
end


  








  

    #run  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1444



def run
  if use_advisory_lock?
    with_advisory_lock { run_without_lock }
  else
    run_without_lock
  end
end


  








  

    #run_without_lock   (private)
  



  

    

Used for running a specific migration.


  





  
Raises:





  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1494



def run_without_lock
  migration = migrations.detect { |m| m.version == @target_version }
  raise UnknownMigrationVersionError.new(@target_version) if migration.nil?

  record_environment
  execute_migration_in_transaction(migration)
end


  








  

    #runnable  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1460



def runnable
  runnable = migrations[start..finish]
  if up?
    runnable.reject { |m| ran?(m) }
  else
    # skip the last migration if we're headed down, but not ALL the way down
    runnable.pop if target
    runnable.find_all { |m| ran?(m) }
  end
end


  








  

    #start   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1553



def start
  up? ? 0 : (migrations.index(current) || 0)
end


  








  

    #target   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1545



def target
  migrations.detect { |m| m.version == @target_version }
end


  








  

    #use_transaction?(migration)  ⇒ Boolean  (private)
  



  

    
  





  


  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1592



def use_transaction?(migration)
  !migration.disable_ddl_transaction && connection.supports_ddl_transactions?
end


  








  

    #validate(migrations)   (private)
  



  

    
  





  
Raises:





  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1557



def validate(migrations)
  name, = migrations.group_by(&:name).find { |_, v| v.length > 1 }
  raise DuplicateMigrationNameError.new(name) if name

  version, = migrations.group_by(&:version).find { |_, v| v.length > 1 }
  raise DuplicateMigrationVersionError.new(version) if version
end


  








  

    #with_advisory_lock   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1600



def with_advisory_lock
  lock_id = generate_migrator_advisory_lock_id

  got_lock = connection.get_advisory_lock(lock_id)
  raise ConcurrentMigrationError unless got_lock
  load_migrated # reload schema_migrations to be sure it wasn't changed by another process before we got the lock
  yield
ensure
  if got_lock && !connection.release_advisory_lock(lock_id)
    raise ConcurrentMigrationError.new(
      ConcurrentMigrationError::RELEASE_LOCK_FAILED_MESSAGE
    )
  end
end