Enforce product nesting level also for the API

migrations/0121.sql

@@ -0,0 +1,10 @@
+CREATE TRIGGER enfore_product_nesting_level BEFORE UPDATE ON products
+BEGIN
+	-- Currently only 1 level is supported
+    SELECT CASE WHEN((
+        SELECT 1
+        FROM products p
+        WHERE IFNULL(NEW.parent_product_id, '') != ''
+            AND IFNULL(parent_product_id, '') = NEW.id
+    ) NOTNULL) THEN RAISE(ABORT, "Unsupported product nesting level detected (currently only 1 level is supported)") END;
+END;