You can now customise the display of empty strings in IfcCSV.

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

@@ -205,6 +205,7 @@ class ExportIfcCsv(bpy.types.Operator):
             delimiter=sep,
             include_global_id=props.include_global_id,
             null=props.null_value,
+            empty=props.empty_value,
             bool_true=props.true_value,
             bool_false=props.false_value,
             sort=sort,
@@ -244,6 +245,7 @@ class ImportIfcCsv(bpy.types.Operator):
             attributes=attributes,
             delimiter=sep,
             null=props.null_value,
+            empty=props.empty_value,
             bool_true=props.true_value,
             bool_false=props.false_value,
         )

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

@@ -69,6 +69,7 @@ class CsvProperties(PropertyGroup):
     should_preserve_existing: BoolProperty(default=False, name="Preserve Existing")
     include_global_id: BoolProperty(default=True, name="Include GlobalId")
     null_value: StringProperty(default="N/A", name="Null Value")
+    empty_value: StringProperty(default="-", name="Empty String Value")
     true_value: StringProperty(default="YES", name="True Value")
     false_value: StringProperty(default="NO", name="False Value")
     csv_delimiter: EnumProperty(

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

@@ -74,6 +74,8 @@ class BIM_PT_ifccsv(Panel):
             row = layout.row()
             row.prop(props, "null_value")
             row = layout.row()
+            row.prop(props, "empty_value")
+            row = layout.row()
             row.prop(props, "true_value")
             row = layout.row()
             row.prop(props, "false_value")

src/ifccsv/ifccsv.py

@@ -70,6 +70,7 @@ class IfcCsv:
         include_global_id=True,
         delimiter=",",
         null="-",
+        empty="",
         bool_true="YES",
         bool_false="NO",
         sort=None,
@@ -96,6 +97,8 @@ class IfcCsv:
                 value = ifcopenshell.util.selector.get_element_value(element, attribute)
                 if value is None:
                     value = null
+                elif value == "":
+                    value = empty
                 elif value is True:
                     value = bool_true
                 elif value is False:
@@ -368,17 +371,17 @@ class IfcCsv:
                 results.update([p.Name for p in element.Quantities])
         return ["{}.{}".format(pset_qto_name, n) for n in results]
 
-    def Import(self, ifc_file, table, attributes=None, delimiter=",", null="-", bool_true="YES", bool_false="NO"):
+    def Import(self, ifc_file, table, attributes=None, delimiter=",", null="-", empty="", bool_true="YES", bool_false="NO"):
         ext = table.split(".")[-1].lower()
 
         if ext == "csv":
-            self.import_csv(ifc_file, table, attributes, delimiter, null, bool_true, bool_false)
+            self.import_csv(ifc_file, table, attributes, delimiter, null, empty, bool_true, bool_false)
         elif ext == "ods":
-            self.import_ods(ifc_file, table, attributes, null, bool_true, bool_false)
+            self.import_ods(ifc_file, table, attributes, null, empty, bool_true, bool_false)
         elif ext == "xlsx":
-            self.import_xlsx(ifc_file, table, attributes, null, bool_true, bool_false)
+            self.import_xlsx(ifc_file, table, attributes, null, empty, bool_true, bool_false)
 
-    def import_csv(self, ifc_file, table, attributes=None, delimiter=",", null="-", bool_true="YES", bool_false="NO"):
+    def import_csv(self, ifc_file, table, attributes=None, delimiter=",", null="-", empty="", bool_true="YES", bool_false="NO"):
         with open(table, newline="", encoding="utf-8") as f:
             reader = csv.reader(f, delimiter=delimiter)
             headers = []
@@ -390,17 +393,17 @@ class IfcCsv:
                     elif len(attributes) == len(headers) - 1:
                         attributes.insert(0, "")  # The GlobalId column
                     continue
-                self.process_row(ifc_file, row, headers, attributes, null, bool_true, bool_false)
+                self.process_row(ifc_file, row, headers, attributes, null, empty, bool_true, bool_false)
 
-    def import_xlsx(self, ifc_file, table, attributes, null, bool_true, bool_false):
+    def import_xlsx(self, ifc_file, table, attributes, null, empty, bool_true, bool_false):
         df = pd.read_excel(table)
-        self.import_pd(ifc_file, df, attributes, null, bool_true, bool_false)
+        self.import_pd(ifc_file, df, attributes, null, empty, bool_true, bool_false)
 
-    def import_ods(self, ifc_file, table, attributes, null, bool_true, bool_false):
+    def import_ods(self, ifc_file, table, attributes, null, empty, bool_true, bool_false):
         df = pd.read_excel(table, engine="odf")
-        self.import_pd(ifc_file, df, attributes, null, bool_true, bool_false)
+        self.import_pd(ifc_file, df, attributes, null, empty, bool_true, bool_false)
 
-    def import_pd(self, ifc_file, df, attributes=None, null="-", bool_true="YES", bool_false="NO"):
+    def import_pd(self, ifc_file, df, attributes=None, null="-", empty="", bool_true="YES", bool_false="NO"):
         headers = df.columns.tolist()
 
         if not attributes:
@@ -409,9 +412,9 @@ class IfcCsv:
             attributes.insert(0, "")  # The GlobalId column
 
         for _, row in df.iterrows():
-            self.process_row(ifc_file, row.tolist(), headers, attributes, null, bool_true, bool_false)
+            self.process_row(ifc_file, row.tolist(), headers, attributes, null, empty, bool_true, bool_false)
 
-    def process_row(self, ifc_file, row, headers, attributes, null, bool_true, bool_false):
+    def process_row(self, ifc_file, row, headers, attributes, null, empty, bool_true, bool_false):
         try:
             element = ifc_file.by_guid(row[0])
         except:
@@ -422,6 +425,8 @@ class IfcCsv:
                 continue  # Skip GlobalId
             if value == null:
                 value = None
+            elif value == empty:
+                value = ""
             elif value == bool_true:
                 value = True
             elif value == bool_false:
@@ -449,7 +454,7 @@ if __name__ == "__main__":
         help="Specify attributes that are part of the extract, using the IfcQuery syntax such as 'class', 'Name' or 'Pset_Foo.Bar'",
     )
     parser.add_argument(
-        "-h", "--headers", nargs="+", help="Specify human readable headers that correlate to each attribute."
+        "--headers", nargs="+", help="Specify human readable headers that correlate to each attribute."
     )
     parser.add_argument("--sort", nargs="+", help="Specify one or more attributes to sort by.")
     parser.add_argument("--order", nargs="+", help="Choose the sort order from ASC or DESC for each sorted attribute.")

src/ifcopenshell-python/docs/ifccsv.rst

@@ -66,7 +66,8 @@ utility:
 ::
 
     $ python -m ifccsv -h
-    usage: ifccsv.py [-h] -i IFC [-s SPREADSHEET] [-f FORMAT] [-d DELIMITER] [-n NULL] [-q QUERY] [-a ARGUMENTS [ARGUMENTS ...]] [--export] [--import]
+    usage: ifccsv.py [-h] -i IFC [-s SPREADSHEET] [-f FORMAT] [-d DELIMITER] [-n NULL] [--bool_true BOOL_TRUE] [--bool_false BOOL_FALSE] [-q QUERY] [-a ATTRIBUTES [ATTRIBUTES ...]] [--headers HEADERS [HEADERS ...]] [--sort SORT [SORT ...]]
+                     [--order ORDER [ORDER ...]] [--export] [--import]
 
     Exports IFC data to and from CSV
 
@@ -80,12 +81,22 @@ utility:
       -d DELIMITER, --delimiter DELIMITER
                             The delimiter in CSV. Defaults to a comma.
       -n NULL, --null NULL  How to represent null values. Defaults to a hyphen.
+      --bool_true BOOL_TRUE
+                            How to represent true values. Defaults to YES.
+      --bool_false BOOL_FALSE
+                            How to represent false values. Defaults to NO.
       -q QUERY, --query QUERY
                             Specify a IFC query selector, such as "IfcWall"
-      -a ARGUMENTS [ARGUMENTS ...], --arguments ARGUMENTS [ARGUMENTS ...]
+      -a ATTRIBUTES [ATTRIBUTES ...], --attributes ATTRIBUTES [ATTRIBUTES ...]
-                            Specify attributes that are part of the extract, using the IfcQuery syntax such as 'type', 'Name' or 'Pset_Foo.Bar'
+                            Specify attributes that are part of the extract, using the IfcQuery syntax such as 'class', 'Name' or 'Pset_Foo.Bar'
-      --export              Export from IFC to CSV
+      --headers HEADERS [HEADERS ...]
-      --import              Import from CSV to IFC
+                            Specify human readable headers that correlate to each attribute.
+      --sort SORT [SORT ...]
+                            Specify one or more attributes to sort by.
+      --order ORDER [ORDER ...]
+                            Choose the sort order from ASC or DESC for each sorted attribute.
+      --export              Export from IFC to the desired format.
+      --import              Import from the autodetected format to IFC.
     $ python -m ifccsv -i model.ifc -s out.csv -f csv -q .IfcProduct -a "Name" "Description" --export
     $ cat out.csv