search for: before_destori

Hey, probably an easy question but, I''m trying to get a method to run "before_destory" for a model, and I want the method to throw an error, and not delete the object from the database, if a certain condition is held Obviously, I can just raise an error and rescue it... but for some reason I can''t get <% error_messages_for ''model" %> to catch

In my rails application,there are two models:post and catalog. One post has a catalog,and one catalog has many posts. When I delete a catalog,the posts belongs to the catalog will not be shown normal,for it''s catalog is no existed. Now I want to create(if the ''Defalut catalog'' is not existed) a ''Defalut catalog'' in catalogs table,and make the