set_element_value - pass attr value to the next part of the query #4495

E.g. previously set_element_value with query "material.item.Material.Name" would fail with error "Material property is expecting an IFC entity and not a string".

But now it will detect that "Material" property is not a last key in the query and will pass `.Material` value forward and try to set it's `.Name` attribute with value.

The main goal is to make sure get_element_value and set_element_value would have a same result for same queries.

src/ifcopenshell-python/ifcopenshell/util/selector.py

@@ -397,8 +397,14 @@ def set_element_value(
             if key == "Name" and element.is_a("IfcMaterialLayerSet"):
                 key = "LayerSetName"  # This oddity in the IFC spec is annoying so we account for it.
 
-            if isinstance(key, str) and hasattr(element, key):
+            if isinstance(key, str) and ((current_value := getattr(element, key, ...)) is not ...):
-                if getattr(element, key) != value:
+                # check if key is not last
+                if len(keys) != i + 1:
+                    element = current_value
+                    continue
+
+                if current_value != value:
+                    # check if key is not last
                     try:
                         # Try our luck
                         return setattr(element, key, value)
@@ -422,6 +428,10 @@ def set_element_value(
                                 value = False
                             else:
                                 value = bool(value)
+                        elif data_type == "entity":
+                            value = ifc_file.by_guid(value)
+                        if current_value == value:
+                            return
                         return setattr(element, key, value)
             else:
                 # Try to extract pset

src/ifcopenshell-python/test/util/test_selector.py

@@ -311,6 +311,13 @@ class TestSetElementValue(test.bootstrap.IFC4):
         subject.set_element_value(self.file, element, "Name", 123)
         assert element.Name == "123"
 
+    def test_set_attributes_attribute(self):
+        material = self.file.create_entity("IfcMaterial")
+        layer = self.file.create_entity("IfcMaterialLayer")
+        layer.Material = material
+        subject.set_element_value(self.file, layer, "Material.Name", "Foo")
+        assert material.Name == "Foo"
+
 
 class TestSelector(test.bootstrap.IFC4):
     def test_selecting_from_specified_elements(self):