ENH: table json converter: timezone handling for datetime

src/caosadvancedtools/table_json_conversion/fill_xlsx.py

@@ -22,6 +22,7 @@
 
 from __future__ import annotations
 
+import datetime
 import pathlib
 from types import SimpleNamespace
 from typing import Any, Optional, TextIO, Union
@@ -155,6 +156,7 @@ class TemplateFiller:
     def _handle_data(self, data: dict, current_path: list[str] = None,
                      context: TemplateFiller.Context = None,
                      only_collect_insertables: bool = False,
+                     utc: bool = False,
                      ) -> Optional[dict[str, Any]]:
         """Handle the data and write it into ``workbook``.
 
@@ -176,6 +178,8 @@ context: TemplateFiller.Context, optional
 only_collect_insertables: bool, optional
   If True, do not insert anything on this level, but return a dict with entries to be inserted.
 
+utc: bool, optional
+  If True, store times as UTC. Else store as local time on a best-effort base.
 
 Returns
 -------
@@ -233,6 +237,13 @@ out: union[dict, None]
                     value = content[0]
                     if isinstance(value, str):
                         value = ILLEGAL_CHARACTERS_RE.sub("", value)
+                    if isinstance(value, datetime.datetime):
+                        if value.tzinfo is not None:
+                            if utc:
+                                value = value.astimezone(datetime.timezone.utc).replace(tzinfo=None)
+                            else:
+                                # Remove timezone, store in local timezone.
+                                value = value.astimezone().replace(tzinfo=None)
 
                 path_str = p2s(path)
                 assert path_str not in insertables