Class: ActiveRecord::Migrator

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# File 'activerecord/lib/active_record/migration.rb', line 436

def down(migrations_path, target_version = nil)
  self.new(:down, migrations_path, target_version).migrate
end

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# File 'activerecord/lib/active_record/migration.rb', line 428

def forward(migrations_path, steps=1)
  move(:up, migrations_path, steps)
end

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# File 'activerecord/lib/active_record/migration.rb', line 452

def get_all_versions
  table = Arel::Table.new(schema_migrations_table_name)
  Base.connection.select_values(table.project(table['version']).to_sql).map{ |v| v.to_i }.sort
end

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# File 'activerecord/lib/active_record/migration.rb', line 412

def migrate(migrations_path, target_version = nil)
  case
    when target_version.nil?
      up(migrations_path, target_version)
    when current_version == 0 && target_version == 0
    when current_version > target_version
      down(migrations_path, target_version)
    else
      up(migrations_path, target_version)
  end
end

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# File 'activerecord/lib/active_record/migration.rb', line 444

def migrations_path
  'db/migrate'
end

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# File 'activerecord/lib/active_record/migration.rb', line 466

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

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# File 'activerecord/lib/active_record/migration.rb', line 424

def rollback(migrations_path, steps=1)
  move(:down, migrations_path, steps)
end

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# File 'activerecord/lib/active_record/migration.rb', line 440

def run(direction, migrations_path, target_version)
  self.new(direction, migrations_path, target_version).run
end

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# File 'activerecord/lib/active_record/migration.rb', line 448

def schema_migrations_table_name
  Base.table_name_prefix + 'schema_migrations' + Base.table_name_suffix
end

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# File 'activerecord/lib/active_record/migration.rb', line 432

def up(migrations_path, target_version = nil)
  self.new(:up, migrations_path, target_version).migrate
end

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# File 'activerecord/lib/active_record/migration.rb', line 491

def current_version
  migrated.last || 0
end

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# File 'activerecord/lib/active_record/migration.rb', line 508

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})" if Base.logger

    # 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

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# File 'activerecord/lib/active_record/migration.rb', line 582

def migrated
  @migrated_versions ||= self.class.get_all_versions
end

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# File 'activerecord/lib/active_record/migration.rb', line 547

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

      migration = MigrationProxy.new
      migration.name     = name.camelize
      migration.version  = version
      migration.filename = file
      klasses << migration
    end

    migrations = migrations.sort_by { |m| m.version }
    down? ? migrations.reverse : migrations
  end
end

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# File 'activerecord/lib/active_record/migration.rb', line 577

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

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# File 'activerecord/lib/active_record/migration.rb', line 499

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