레일 4.2.3을 사용하고 있습니다. 테이블과 동일한 유형의 테이블에 열을 추가하는 마이그레이션을 어떻게 만듭니 까? 또한 외래 키를 추가하려면 어떻게해야합니까? (열이 NULL이면 괜찮습니까?) 나는이레일스에서 테이블과 동일한 유형의 테이블에 열/외래 키를 추가하는 마이그레이션을 어떻게 만듭니 까?
class AddLinkedMyObjectToMyObjects < ActiveRecord::Migration
def change
add_reference :my_objects, :linked_my_object, type: :my_object, index: true, foreign_key: true
end
end
을 시도하지만 난
== 20160616201701 AddLinkedMyObjectToMyObjects: migrating =============================
-- add_reference(:my_objects, :linked_my_object, {:type=>:my_object, :index=>true, :foreign_key=>true})
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:
PG::UndefinedObject: ERROR: type "my_object" does not exist
LINE 1: ALTER TABLE "MyObjects" ADD "linked_my_object_id" my_object
^
: ALTER TABLE "MyObjects" ADD "linked_my_object_id" my_object
/Users/davea/.rvm/gems/[email protected]/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `async_exec'
/Users/davea/.rvm/gems/[email protected]/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `block in execute'
/Users/davea/.rvm/gems/[email protected]/gems/activerecord-4.2.5.1/lib/active_record/connection_adapters/abstract_adapter.rb:472:in `block in log'