Fix #4434. User can now explicitly select whether they are choosing a whole or part when changing the aggregate.

src/blenderbim/blenderbim/bim/module/aggregate/operator.py

@@ -40,11 +40,16 @@ class BIM_OT_aggregate_assign_object(bpy.types.Operator, Operator):
     bl_label = "Assign Object To Aggregation"
     bl_options = {"REGISTER", "UNDO"}
     relating_object: bpy.props.IntProperty()
+    related_object: bpy.props.IntProperty()
 
     def _execute(self, context):
         relating_obj = None
         if self.relating_object:
             relating_obj = tool.Ifc.get_object(tool.Ifc.get().by_id(self.relating_object))
+        elif self.related_object:
+            aggregate = ifcopenshell.util.element.get_aggregate(tool.Ifc.get().by_id(self.related_object))
+            if aggregate:
+                relating_obj = tool.Ifc.get_object(aggregate)
         elif context.active_object:
             relating_obj = context.active_object
         if not relating_obj:

src/blenderbim/blenderbim/bim/module/aggregate/prop.py

@@ -34,15 +34,27 @@ from bpy.props import (
 
 def update_relating_object(self, context):
     def message(self, context):
-        self.layout.label(text="Please select a valid Ifc Element")
+        self.layout.label(text="Please select a valid IFC Element")
 
-    if self.relating_object is None:
-        return
-    if not self.relating_object.BIMObjectProperties.ifc_definition_id:
-        context.window_manager.popup_menu(message, title="Invalid Element Selected", icon="INFO")
+    if self.relating_object:
+        self.related_object = None
+        if not self.relating_object.BIMObjectProperties.ifc_definition_id:
+            context.window_manager.popup_menu(message, title="Invalid Element Selected", icon="INFO")
+            self.relating_object = None
+
+
+def update_related_object(self, context):
+    def message(self, context):
+        self.layout.label(text="Please select a valid IFC Element")
+
+    if self.related_object:
         self.relating_object = None
+        if not self.related_object.BIMObjectProperties.ifc_definition_id:
+            context.window_manager.popup_menu(message, title="Invalid Element Selected", icon="INFO")
+            self.related_object = None
 
 
 class BIMObjectAggregateProperties(PropertyGroup):
     is_editing: BoolProperty(name="Is Editing")
-    relating_object: PointerProperty(name="Aggregate", type=bpy.types.Object, update=update_relating_object)
+    relating_object: PointerProperty(name="Relating Whole", type=bpy.types.Object, update=update_relating_object)
+    related_object: PointerProperty(name="Related Part", type=bpy.types.Object, update=update_related_object)

src/blenderbim/blenderbim/bim/module/aggregate/ui.py

@@ -53,12 +53,21 @@ class BIM_PT_aggregate(Panel):
         props = context.active_object.BIMObjectAggregateProperties
 
         if props.is_editing:
+            row = layout.row()
+            row.prop(props, "relating_object", text="Whole")
+            row = layout.row()
+            row.prop(props, "related_object", text="Or Part")
             row = layout.row(align=True)
-            row.prop(props, "relating_object", text="")
+            col = row.column(align=True)
+            if not props.relating_object and not props.related_object:
+                col.enabled = False
+            op = col.operator("bim.aggregate_assign_object", icon="CHECKMARK")
             if props.relating_object:
-                op = row.operator("bim.aggregate_assign_object", icon="CHECKMARK", text="")
                 op.relating_object = props.relating_object.BIMObjectProperties.ifc_definition_id
+            elif props.related_object:
+                op.related_object = props.related_object.BIMObjectProperties.ifc_definition_id
             row.operator("bim.disable_editing_aggregate", icon="CANCEL", text="")
+            return
         else:
             row = layout.row(align=True)
             if AggregateData.data["has_relating_object"]:
@@ -73,7 +82,7 @@ class BIM_PT_aggregate(Panel):
                 row.operator("bim.add_aggregate", icon="ADD", text="")
                 op = row.operator("bim.aggregate_unassign_object", icon="X", text="")
             else:
-                row.label(text="No Whole relation defined", icon="TRIA_UP")
+                row.label(text="No Whole Relationship Found", icon="TRIA_UP")
                 row.operator("bim.enable_editing_aggregate", icon="GREASEPENCIL", text="")
                 row.operator("bim.add_aggregate", icon="ADD", text="")