Format datetime values as ISO8601 during attribute expansion (#1)

dftimewolf/lib/utils.py

@@ -3,6 +3,7 @@
 
 import abc
 import argparse
+import datetime
 import os
 import random
 import re
@@ -102,6 +103,10 @@ def ImportArgsFromDict(value: Any,
   It is used to load arguments from the CLI and any extra configuration
   parameters passed in recipes.
 
+  When a token resolves to a ``datetime.datetime`` and the recipe value is
+  solely ``@token``, the datetime object is preserved. When the token is
+  embedded in a larger string, it is formatted as an ISO8601 timestamp.
+
   Args:
     value (object): The value a dictionary. This is passed recursively and may
         change in nature: string, list, or dict. The top-level variable should
@@ -120,6 +125,14 @@ def ImportArgsFromDict(value: Any,
         actual_param = args[token]
         if isinstance(actual_param, str):
           value = value.replace("@"+token, actual_param)
+        elif isinstance(actual_param, datetime.datetime):
+          # Keep datetime objects when the recipe arg is solely "@token" so
+          # modules that expect datetime continue to receive them. When the
+          # token is embedded in a larger string, expand to ISO8601.
+          if value == f'@{token}':
+            value = actual_param
+          else:
+            value = value.replace('@' + token, actual_param.isoformat())
         else:
           value = actual_param
   elif isinstance(value, list):

tests/test_dftimewolf.py

@@ -2,6 +2,7 @@
 """Tests for DFTimewolf functions."""
 
 import argparse
+import datetime
 import unittest
 
 import six
@@ -139,3 +140,37 @@ def test_config_fills_missing_args(self):
     imported_args = dftw_utils.ImportArgsFromDict(
         provided_args, vars(args), config.Config)
     self.assertEqual(imported_args, expected_args)
+
+  def test_datetime_token_preserves_object(self):
+    """Tests that a sole @datetime token remains a datetime object."""
+    start_date = datetime.datetime(
+        2024, 1, 1, 12, 0, 0, tzinfo=datetime.timezone.utc)
+    recipe_args = {'start_time': '@start_date'}
+    imported_args = dftw_utils.ImportArgsFromDict(
+        recipe_args, {'start_date': start_date}, config.Config)
+
+    self.assertIs(imported_args['start_time'], start_date)
+
+  def test_datetime_tokens_expand_to_iso8601_in_strings(self):
+    """Tests that datetime tokens embedded in strings expand to ISO8601."""
+    start_date = datetime.datetime(
+        2024, 1, 1, 12, 0, 0, tzinfo=datetime.timezone.utc)
+    end_date = datetime.datetime(
+        2024, 1, 2, 18, 30, 45, tzinfo=datetime.timezone.utc)
+    recipe_args = {
+        'sheet_title': 'example @start_date @end_date',
+    }
+    expected_args = {
+        'sheet_title': (
+            f'example {start_date.isoformat()} {end_date.isoformat()}'),
+    }
+
+    imported_args = dftw_utils.ImportArgsFromDict(
+        recipe_args,
+        {'start_date': start_date, 'end_date': end_date},
+        config.Config)
+
+    self.assertEqual(imported_args, expected_args)
+    self.assertEqual(
+        imported_args['sheet_title'],
+        'example 2024-01-01T12:00:00+00:00 2024-01-02T18:30:45+00:00')