From 2d53c691f59fd1a0cb45a4f90f144f258e9a8340 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Tue, 4 Feb 2020 11:55:54 +1100
Subject: [PATCH] Prevent duplicate GlobalIds if the author manually creates a
 collision

---
 src/ifcblenderexport/blenderbim/export_ifc.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/ifcblenderexport/blenderbim/export_ifc.py b/src/ifcblenderexport/blenderbim/export_ifc.py
index 570562e87c..37542d9036 100644
--- a/src/ifcblenderexport/blenderbim/export_ifc.py
+++ b/src/ifcblenderexport/blenderbim/export_ifc.py
@@ -77,6 +77,7 @@ class IfcParser():
 
         self.selected_products = []
         self.selected_spatial_structure_elements = []
+        self.global_ids = []
 
         self.product_index = 0
         self.product_name_index_map = {}
@@ -195,11 +196,15 @@ class IfcParser():
 
     def get_object_attributes(self, obj):
         attributes = {'Name': self.get_ifc_name(obj.name)}
-        if obj.BIMObjectProperties.attributes.find('GlobalId') == -1:
+        global_id_index = obj.BIMObjectProperties.attributes.find('GlobalId')
+        if global_id_index == -1:
             global_id = obj.BIMObjectProperties.attributes.add()
             global_id.name = 'GlobalId'
             global_id.string_value = ifcopenshell.guid.new()
+        elif obj.BIMObjectProperties.attributes[global_id_index].string_value in self.global_ids:
+            obj.BIMObjectProperties.attributes[global_id_index].string_value = ifcopenshell.guid.new()
         attributes.update({a.name: a.string_value for a in obj.BIMObjectProperties.attributes})
+        self.global_ids.append(attributes['GlobalId'])
         return attributes
 
     def get_products(self):