Fix #3589. Users can now configure how the null values are represented in IfcCSV.

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

@@ -153,7 +153,15 @@ class ExportIfcCsv(bpy.types.Operator):
         ifc_csv = ifccsv.IfcCsv()
         attributes = [a.name for a in props.csv_attributes]
         sep = props.csv_custom_delimiter if props.csv_delimiter == "CUSTOM" else props.csv_delimiter
-        ifc_csv.export(ifc_file, results, attributes, output=self.filepath, format=props.format, delimiter=sep)
+        ifc_csv.export(
+            ifc_file,
+            results,
+            attributes,
+            output=self.filepath,
+            format=props.format,
+            delimiter=sep,
+            null=props.null_value,
+        )
         return {"FINISHED"}
 
 
@@ -179,7 +187,7 @@ class ImportIfcCsv(bpy.types.Operator):
             ifc_file = ifcopenshell.open(props.csv_ifc_file)
         ifc_csv = ifccsv.IfcCsv()
         sep = props.csv_custom_delimiter if props.csv_delimiter == "CUSTOM" else props.csv_delimiter
-        ifc_csv.Import(ifc_file, self.filepath, delimiter=sep)
+        ifc_csv.Import(ifc_file, self.filepath, delimiter=sep, null=props.null_value)
         if not props.should_load_from_memory:
             ifc_file.write(props.csv_ifc_file)
         purge_module_data()

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

@@ -35,6 +35,7 @@ class CsvProperties(PropertyGroup):
     csv_ifc_file: StringProperty(default="", name="IFC File")
     ifc_selector: StringProperty(default="", name="IFC Selector")
     csv_attributes: CollectionProperty(name="CSV Attributes", type=StrProperty)
+    null_value: StringProperty(default="N/A", name="Null Value")
     csv_delimiter: EnumProperty(
         items=[
             (";", ";", ""),

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

@@ -72,6 +72,9 @@ class BIM_PT_ifccsv(Panel):
                 row = layout.row(align=True)
                 row.prop(props, "csv_custom_delimiter")
 
+        row = layout.row(align=True)
+        row.prop(props, "null_value")
+
         row = layout.row()
         split = row.split(factor=0.5)
         c = split.column()