如何在Rails遷移中創建觸發器？

Question

我正在嘗試向PostgreSQL（v 9）db添加一些觸發器，我想創建一個Rails遷移（使用v 4.2.7）來滿足這個目標。 所以我用這個內容創建了一個遷移

class CreateDeleteAddressTriggers < ActiveRecord::Migration
  def change
    execute <<-SQL
      CREATE OR REPLACE FUNCTION remove_address() RETURNS trigger
        LANGUAGE plpgsql AS
        $$BEGIN
          DELETE FROM public.addresses WHERE id = OLD.address_id;
      END;$$;

      CREATE TRIGGER remove_my_object_address
        AFTER DELETE ON public.my_objects FOR EACH ROW
        EXECUTE TRIGGER remove_address()

      CREATE TRIGGER remove_user_address
        AFTER DELETE ON public.users FOR EACH ROW
        EXECUTE TRIGGER remove_address()
    SQL
  end
end

不幸的是，當我運行“rake db：migrate”任務時，我收到以下錯誤

davea$ rake db:migrate
== 20160928184431 CreateDeleteAddressTriggers: migrating ======================
-- execute("      CREATE OR REPLACE FUNCTION remove_address() RETURNS trigger\n        LANGUAGE plpgsql AS\n        $$BEGIN\n          DELETE FROM public.addresses WHERE id =  OLD.address_id;\n      END;$$;\n\n      CREATE TRIGGER remove_my_object_address\n        AFTER DELETE ON public.my_objects FOR EACH ROW\n        EXECUTE TRIGGER remove_address()\n\n       CREATE TRIGGER remove_user_address\n        AFTER DELETE ON public.users FOR EACH ROW\n        EXECUTE TRIGGER remove_address()\n")
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

PG::SyntaxError: ERROR:  syntax error at or near "TRIGGER"
LINE 9:         EXECUTE TRIGGER remove_address()
                        ^
:       CREATE OR REPLACE FUNCTION remove_address() RETURNS trigger
        LANGUAGE plpgsql AS
        $$BEGIN
          DELETE FROM public.addresses WHERE id = OLD.address_id;
      END;$$;

      CREATE TRIGGER remove_my_object_address
        AFTER DELETE ON public.my_objects FOR EACH ROW
        EXECUTE TRIGGER remove_address()

      CREATE TRIGGER remove_user_address
        AFTER DELETE ON public.users FOR EACH ROW
        EXECUTE TRIGGER remove_address()
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `async_exec'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:155:in `block in execute'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/abstract_adapter.rb:484:in `block in log'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activesupport-4.2.7.1/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/abstract_adapter.rb:478:in `log'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:154:in `execute'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/migration.rb:665:in `block in method_missing'
/Users/davea/.rvm/gems/ruby-2.3.0/gems/activerecord-4.2.7.1/lib/active_record/migration.rb:634:in `block in say_with_time'

如何更正我的遷移以正確運行觸發器？

編輯：回答給出的答案，這是產生的錯誤......

ActiveRecord::StatementInvalid: PG::SyntaxError: ERROR:  syntax error at or near "CREATE"
LINE 11:       CREATE TRIGGER remove_user_address

Answer 1

您在SQL中使用了錯誤的語法。 你需要EXECUTE PROCEDURE ，而不是EXECUTE TRIGGER 。

你應該有

  CREATE TRIGGER remove_my_object_address
    AFTER DELETE ON public.my_objects FOR EACH ROW
    EXECUTE PROCEDURE remove_address()
            ^^^^^^^^^

和

 CREATE TRIGGER remove_user_address
    AFTER DELETE ON public.users FOR EACH ROW
    EXECUTE PROCEDURE remove_address()
            ^^^^^^^^^

來源： PostgreSQL文檔 。