deriveDynamicFieldID function

String deriveDynamicFieldID(String parentId, String nameType, Uint8List nameBcs)

Derive the object ID of a dynamic field on parentId with the given field name type (nameType, e.g. u64 or 0x2::foo::Bar) and BCS-encoded name value (nameBcs).

Mirrors deriveDynamicFieldID in the TypeScript SDK: blake2b(0xf0 || parent || u64(len(key)) || key || typeTag)[0..32].

Implementation

String deriveDynamicFieldID(
  String parentId,
  String nameType,
  Uint8List nameBcs,
) {
  final address = SuiBcs.Address.serialize(parentId).toBytes();
  final tag = SuiBcs.TypeTag.serialize(nameType).toBytes();
  final keyLength = SuiBcs.U64.serialize(nameBcs.length).toBytes();

  final buf = <int>[
    0xf0,
    ...address,
    ...keyLength,
    ...nameBcs,
    ...tag,
  ];

  final hash = blake2b(buf);
  return '0x${HEX.encode(hash.sublist(0, 32))}';
}