class ActiveRecord::MigrationContext
MigrationContext
sets the context in which a migration is run.
A migration context requires the path to the migrations is set in the migrations_paths
parameter. Optionally a schema_migration
class can be provided. For most applications, SchemaMigration
is sufficient. Multiple database applications need a SchemaMigration
per primary database.
Attributes
Public Class Methods
Source
# File lib/active_record/migration.rb, line 1120 def initialize(migrations_paths, schema_migration = SchemaMigration) @migrations_paths = migrations_paths @schema_migration = schema_migration end
Public Instance Methods
Source
# File lib/active_record/migration.rb, line 1138 def migrate(target_version = nil, &block) case when target_version.nil? up(target_version, &block) when current_version == 0 && target_version == 0 [] when current_version > target_version down(target_version, &block) else up(target_version, &block) end end
Runs the migrations in the migrations_path
.
If target_version
is nil
, migrate
will run up
.
If the current_version
and target_version
are both 0 then an empty array will be returned and no migrations will be run.
If the current_version
in the schema is greater than the target_version
, then down
will be run.
If none of the conditions are met, up
will be run with the target_version
.
Private Instance Methods
Source
# File lib/active_record/migration.rb, line 1258 def migration_files paths = Array(migrations_paths) Dir[*paths.flat_map { |path| "#{path}/**/[0-9]*_*.rb" }] end
Source
# File lib/active_record/migration.rb, line 1267 def move(direction, steps) migrator = Migrator.new(direction, migrations, schema_migration) if current_version != 0 && !migrator.current_migration raise UnknownMigrationVersionError.new(current_version) end start_index = if current_version == 0 0 else migrator.migrations.index(migrator.current_migration) end finish = migrator.migrations[start_index + steps] version = finish ? finish.version : 0 public_send(direction, version) end
Source
# File lib/active_record/migration.rb, line 1263 def parse_migration_filename(filename) File.basename(filename).scan(Migration::MigrationFilenameRegexp).first end