catalogue operations, db migr and so on.

pre release version.

misc/mapper.py

@@ -0,0 +1,11 @@
+def parse_cat_id(value: str) -> int | None | bool:
+    if value == "root":
+        return None
+    if str(value).isdigit():
+        return int(value)
+
+    raise Exception("Invalid Category Id.")
+
+
+def serialize_cat_id(cat_id: int | None) -> str:
+    return "root" if cat_id is None else str(cat_id)