flushing to ensure all data from the TextIOWrapper is written to the …

…underlying BytesIO buffer

kolibri/core/auth/management/commands/bulkexportusers.py

@@ -166,7 +166,8 @@ def csv_file_generator(facility, filepath, overwrite=True):
     csv_file = io.BytesIO()
 
     with csv_file as f:
-        writer = csv.DictWriter(io.TextIOWrapper(f, encoding="utf-8"), header_labels)
+        buffer = io.TextIOWrapper(f, encoding="utf-8")
+        writer = csv.DictWriter(buffer, header_labels)
         logger.info("Creating users csv file {filename}".format(filename=filepath))
         writer.writeheader()
         usernames = set()
@@ -207,6 +208,7 @@ def csv_file_generator(facility, filepath, overwrite=True):
                 usernames.add(item["username"])
             yield item
 
+        buffer.flush()  # Ensure all data is written to the underlying BytesIO
         f.seek(0)
         file = file_storage.save(filename, f)