Class: ActiveRecord::Migrator

Inherits:
Object
  • Object
show all
Defined in:
lib/active_record/migration.rb

Overview

:nodoc:

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(direction, migrations_path, target_version = nil) ⇒ Migrator

Returns a new instance of Migrator.

Raises:

  • (StandardError) 


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# File 'lib/active_record/migration.rb', line 439

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

Class Method Details

.current_version ⇒ Object 



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

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

.down(migrations_path, target_version = nil) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 404

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

.get_all_versions ⇒ Object 



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# File 'lib/active_record/migration.rb', line 420

def get_all_versions
  Base.connection.select_values("SELECT version FROM #{schema_migrations_table_name}").map(&:to_i).sort
end

.migrate(migrations_path, target_version = nil) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 381

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

.migrations_path ⇒ Object 



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

def migrations_path
  'db/migrate'
end

.proper_table_name(name) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 433

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

.rollback(migrations_path, steps = 1) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 390

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

.run(direction, migrations_path, target_version) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 408

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

.schema_migrations_table_name ⇒ Object 



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# File 'lib/active_record/migration.rb', line 416

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

.up(migrations_path, target_version = nil) ⇒ Object 



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# File 'lib/active_record/migration.rb', line 400

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

Instance Method Details

#current_migration ⇒ Object 



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# File 'lib/active_record/migration.rb', line 449

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

#current_version ⇒ Object 



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# File 'lib/active_record/migration.rb', line 445

def current_version
  migrated.last || 0
end

#migrate ⇒ Object 



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# File 'lib/active_record/migration.rb', line 462

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

#migrated ⇒ Object 



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# File 'lib/active_record/migration.rb', line 536

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

#migrations ⇒ Object 



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# File 'lib/active_record/migration.rb', line 501

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 << (MigrationProxy.new).tap 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

#pending_migrations ⇒ Object 



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# File 'lib/active_record/migration.rb', line 531

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

#run ⇒ Object

Raises:



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# File 'lib/active_record/migration.rb', line 453

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