P5-1677. 3b Make sure the canonical settings on categories in admin works and implement the backend logic.

migrations/000.049.sql

@@ -0,0 +1,11 @@
+-- P5-1677 3b Make sure the canonical settings on categories in admin works and implement the backend logic
+
+-- Adding primary key
+ALTER TABLE category_metadata ADD PRIMARY KEY (category_id);
+
+ALTER TABLE category_metadata
+  ALTER COLUMN canonical DROP DEFAULT,
+  ALTER COLUMN canonical TYPE integer USING (CASE WHEN canonical = '' THEN NULL ELSE canonical::integer END),
+  ADD CONSTRAINT categories_category_metadata_canonical_fk FOREIGN KEY (canonical)
+REFERENCES public.categories (id)
+ON UPDATE CASCADE ON DELETE SET NULL;