Merge pull request #366 from emmo-repo/warning-relation-excelparser

Warning relation excelparser

ontopy/excelparser.py

@@ -282,9 +282,12 @@ def create_ontology_from_pandas(  # pylint:disable=too-many-locals,too-many-bran
                     )
 
     # Add properties in a second loop
+
     for index in added_rows:
         row = data.loc[index]
         properties = row["Relations"]
+        if properties == "nan":
+            properties = None
         if isinstance(properties, str):
             try:
                 concept = onto.get_by_label(row["prefLabel"].strip())
@@ -301,10 +304,15 @@ def create_ontology_from_pandas(  # pylint:disable=too-many-locals,too-many-bran
                         f"Error is {exc}."
                     )
                 except NoSuchLabelError as exc:
+                    msg = (
+                        f"Error in Property assignment for: {concept}. "
+                        f"Property to be Evaluated: {prop}. "
+                        f"Error is {exc}."
+                    )
                     if force is True:
-                        pass
+                        warnings.warn(msg)
                     else:
-                        raise ExcelError(exc) from exc
+                        raise ExcelError(msg) from exc
 
     # Synchronise Python attributes to ontology
     onto.sync_attributes(