li7y/migrations/20240711110525_item_class_simplify.down.sql

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-- SPDX-FileCopyrightText: 2024 Simon Bruder <simon@sbruder.de>
--
-- SPDX-License-Identifier: AGPL-3.0-or-later
DROP TRIGGER prevent_item_class_recursion ON item_classes;
DROP FUNCTION check_item_class_recursion_depth;
CREATE TYPE item_class_type AS ENUM ('generic', 'specific');
ALTER TABLE item_classes
ADD type item_class_type;
UPDATE item_classes SET type='generic' WHERE parent IS NULL;
UPDATE item_classes SET type='specific' WHERE parent IS NOT NULL;
ALTER TABLE item_classes
ALTER type SET NOT NULL;
ALTER TABLE item_classes
ALTER type SET DEFAULT 'generic';
ALTER TABLE item_classes
ADD CONSTRAINT parent_only_for_specific CHECK (type = 'generic' AND parent IS NULL OR type = 'specific' AND parent IS NOT NULL);
CREATE FUNCTION check_item_class_parent()
RETURNS TRIGGER AS $$
BEGIN
IF NEW.parent IS NULL THEN
RETURN NEW;
END IF;
IF (SELECT type FROM item_classes WHERE id = NEW.parent) = 'generic' THEN
RETURN NEW;
END IF;
RAISE EXCEPTION 'Specific item classes may only have a generic parent (to avoid recursion)';
END;
$$ LANGUAGE plpgsql;
CREATE TRIGGER prevent_item_class_recursion
BEFORE INSERT OR UPDATE ON item_classes
FOR EACH ROW
EXECUTE FUNCTION check_item_class_parent();