Fix empty scene serialisation

Author: tomvanmele

CHANGELOG.md

@@ -19,6 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed import errors in `compas_rhino.conduits` for Rhino 8.
 * Fixed doctest failures.
 * Fixed bug in serialization when `compas.datastructures.attributes.AttributeView` is used.
+* Fixed bug in the serialisation of empty scenes.
 
 ### Removed
 

src/compas/scene/scene.py

@@ -56,7 +56,7 @@ def __from_data__(cls, data):
         items = {str(item.guid): item for item in data["items"]}
 
         def add(node, parent, items):
-            for child_node in node["children"]:
+            for child_node in node.get("children", []):
                 guid = child_node["item"]
                 settings = child_node["settings"]
                 sceneobject = parent.add(items[guid], **settings)

tests/compas/scene/test_scene_serialisation.py

@@ -115,3 +115,9 @@ def test_scene_serialisation(items, mocker):
 
         scene2 = Scene.from_jsonstring(scene1.to_jsonstring())
         assert assert_is_data_equal(scene1, scene2)
+
+    def test_scene_serialisation_empty():
+        scene = Scene()
+        scene = compas.json_loads(compas.json_dumps(scene))
+
+        assert isinstance(scene, Scene)