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Class: ActiveRecord::MigrationContext

Relationships & Source Files
Inherits: Object
Defined in: activerecord/lib/active_record/migration.rb

Overview

Migration Context

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. Multiple database applications will instantiate a SchemaMigration object per database. From the Rake tasks, Rails will handle this for you.

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(migrations_paths, schema_migration = nil, internal_metadata = nil) ⇒ MigrationContext

[ GitHub ] 

  


# File 'activerecord/lib/active_record/migration.rb', line 1205



def initialize(migrations_paths, schema_migration = nil, internal_metadata = nil)
  if schema_migration == SchemaMigration
    ActiveRecord.deprecator.warn(<<-MSG.squish)
      SchemaMigration no longer inherits from ActiveRecord::Base. If you want
      to use the default connection, remove this argument. If you want to use a
      specific connection, instantiate MigrationContext with the connection's schema
      migration, for example `MigrationContext.new(path, Dog.connection.schema_migration)`.
    MSG

    schema_migration = nil
  end

  if internal_metadata == InternalMetadata
    ActiveRecord.deprecator.warn(<<-MSG.squish)
      SchemaMigration no longer inherits from ActiveRecord::Base. If you want
      to use the default connection, remove this argument. If you want to use a
      specific connection, instantiate MigrationContext with the connection's internal
      metadata, for example `MigrationContext.new(path, nil, Dog.connection.internal_metadata)`.
    MSG

    internal_metadata = nil
  end

  @migrations_paths = migrations_paths
  @schema_migration = schema_migration || SchemaMigration.new(connection)
  @internal_metadata = internal_metadata || InternalMetadata.new(connection)
end


  







Instance Attribute Details



  

    #internal_metadata   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1203



attr_reader :migrations_paths, :schema_migration, :internal_metadata


  








  

    #migrations_paths   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1203



attr_reader :migrations_paths, :schema_migration, :internal_metadata


  








  

    #needs_migration?  ⇒ Boolean  (readonly)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1308



def needs_migration? # :nodoc:
  pending_migration_versions.size > 0
end


  








  

    #protected_environment?  ⇒ Boolean  (readonly)
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1351



def protected_environment? # :nodoc:
  ActiveRecord::Base.protected_environments.include?(last_stored_environment) if last_stored_environment
end


  








  

    #schema_migration   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1203



attr_reader :migrations_paths, :schema_migration, :internal_metadata


  







Instance Method Details



  

    #connection   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1366



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


  








  

    #current_environment  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1347



def current_environment # :nodoc:
  ActiveRecord::ConnectionHandling::DEFAULT_ENV.call
end


  








  

    #current_version  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1303



def current_version # :nodoc:
  get_all_versions.max || 0
rescue ActiveRecord::NoDatabaseError
end


  








  

    #down(target_version = nil, &block)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1277



def down(target_version = nil, &block) # :nodoc:
  selected_migrations = if block_given?
    migrations.select(&block)
  else
    migrations
  end

  Migrator.new(:down, selected_migrations, schema_migration, internal_metadata, target_version).migrate
end


  








  

    #forward(steps = 1)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1263



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


  








  

    #get_all_versions  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1295



def get_all_versions # :nodoc:
  if schema_migration.table_exists?
    schema_migration.integer_versions
  else
    []
  end
end


  








  

    #last_stored_environment  
  

  

    This method is for internal use only.
  



  

    
  





  
Raises:





  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1355



def last_stored_environment # :nodoc:
  return nil unless connection.internal_metadata.enabled?
  return nil if current_version == 0
  raise NoEnvironmentInSchemaError unless connection.internal_metadata.table_exists?

  environment = connection.internal_metadata[:environment]
  raise NoEnvironmentInSchemaError unless environment
  environment
end


  








  

    #migrate(target_version = nil, &block)  
  



  

    

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.


  



  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1246



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


  








  

    #migration_files   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1370



def migration_files
  paths = Array(migrations_paths)
  Dir[*paths.flat_map { |path| "#{path}/**/[0-9]*_*.rb" }]
end


  








  

    #migrations  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1316



def migrations # :nodoc:
  migrations = migration_files.map do |file|
    version, name, scope = parse_migration_filename(file)
    raise IllegalMigrationNameError.new(file) unless version
    version = version.to_i
    name = name.camelize

    MigrationProxy.new(name, version, file, scope)
  end

  migrations.sort_by(&:version)
end


  








  

    #migrations_status  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1329



def migrations_status # :nodoc:
  db_list = schema_migration.normalized_versions

  file_list = migration_files.filter_map do |file|
    version, name, scope = parse_migration_filename(file)
    raise IllegalMigrationNameError.new(file) unless version
    version = schema_migration.normalize_migration_number(version)
    status = db_list.delete(version) ? "up" : "down"
    [status, version, (name + scope).humanize]
  end

  db_list.map! do |version|
    ["up", version, "********** NO FILE **********"]
  end

  (db_list + file_list).sort_by { |_, version, _| version.to_i }
end


  








  

    #move(direction, steps)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1379



def move(direction, steps)
  migrator = Migrator.new(direction, migrations, schema_migration, internal_metadata)

  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


  








  

    #open  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1291



def open # :nodoc:
  Migrator.new(:up, migrations, schema_migration, internal_metadata)
end


  








  

    #parse_migration_filename(filename)   (private)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1375



def parse_migration_filename(filename)
  File.basename(filename).scan(Migration::MigrationFilenameRegexp).first
end


  








  

    #pending_migration_versions  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1312



def pending_migration_versions # :nodoc:
  migrations.collect(&:version) - get_all_versions
end


  








  

    #rollback(steps = 1)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1259



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


  








  

    #run(direction, target_version)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1287



def run(direction, target_version) # :nodoc:
  Migrator.new(direction, migrations, schema_migration, internal_metadata, target_version).run
end


  








  

    #up(target_version = nil, &block)  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/migration.rb', line 1267



def up(target_version = nil, &block) # :nodoc:
  selected_migrations = if block_given?
    migrations.select(&block)
  else
    migrations
  end

  Migrator.new(:up, selected_migrations, schema_migration, internal_metadata, target_version).migrate
end