Default to root node when parent is None

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "python_thingset"
-version = "0.5.1"
+version = "0.5.2"
 description = "A Python library for ThingSet functionality"
 authors = [
     { name = "Adam Mitchell", email = "adam.mitchell@brillpower.com" }

python_thingset/encoders/binary.py

@@ -14,6 +14,7 @@
 
 class ThingSetBinaryEncoder(object):
     NULL_BYTE = 0xF6
+    ROOT_ID   = 0x00
 
     def __init__(self):
         pass
@@ -62,7 +63,17 @@ def encode_exec(self, value_id: int, args: List[Union[Any, None]]) -> bytes:
             + list(cbor2.dumps(p_args, canonical=True))
         )
 
-    def encode_update(self, parent_id: int, value_id: int, value: Any) -> bytes:
+    def encode_update(
+        self, parent_id: Union[int, None], value_id: int, value: Any
+    ) -> bytes:
+        """Update request: ``07 <parent id> {value_id: value}``.
+
+        ``parent_id`` is the containing group; ``None`` means the object sits
+        at the root and is addressed via the root node (ID 0). A CBOR null is
+        never a valid endpoint — the device rejects it with BAD_REQUEST before
+        looking at the map — so it must not be emitted for a missing parent."""
+        if parent_id is None:
+            parent_id = self.ROOT_ID
         value = self._coerce_value(value)
 
         return bytes(

tests/encoders/binary/test_enc_bin_update.py

@@ -62,3 +62,16 @@ def test_update_list_of_strings():
     encoded = encoder.encode_update(0x0, 0x4F, ["a", "b"])
     expected = bytes([0x07]) + cbor2.dumps(0x0) + cbor2.dumps({0x4F: ["a", "b"]}, canonical=True)
     assert encoded == expected
+
+
+def test_update_no_parent_targets_root():
+    # A root-level object has no containing group: the request must address
+    # the root node (ID 0), never a CBOR null endpoint.
+    encoded = encoder.encode_update(None, 0x4F, 1)
+    assert encoded == encoder.encode_update(0x0, 0x4F, 1)
+    assert encoded[1] == 0x00
+
+
+def test_update_native_bool_false():
+    encoded = encoder.encode_update(0x0, 0x4F, False)
+    assert encoded == b"\x07\x00\xa1\x18\x4f\xf4"