feat: improve format_date with fallback value

freqtrade/util/datetime_helpers.py

@@ -90,15 +90,16 @@ def dt_humanize_delta(dt: datetime):
     return humanize.naturaltime(dt)
 
 
-def format_date(date: datetime | None) -> str:
+def format_date(date: datetime | None, fallback: str = "") -> str:
     """
     Return a formatted date string.
     Returns an empty string if date is None.
     :param date: datetime to format
+    :param fallback: value to return if date is None
     """
     if date:
         return date.strftime(DATETIME_PRINT_FORMAT)
-    return ""
+    return fallback
 
 
 def format_ms_time(date: int | float) -> str:

tests/util/test_datetime_helpers.py

@@ -108,6 +108,7 @@ def test_format_date() -> None:
     date = datetime(2021, 9, 30, 22, 59, 3, 455555, tzinfo=UTC)
     assert format_date(date) == "2021-09-30 22:59:03"
     assert format_date(None) == ""
+    assert format_date(None, "closed") == "closed"
 
 
 def test_format_ms_time_detailed() -> None: