feat: handle no date/time/datetime string given

program/utils.py

@@ -32,10 +32,16 @@ if typing.TYPE_CHECKING:
     from program.models import Host, Note, Show
 
 
-def parse_datetime(date_string: str) -> datetime:
+def parse_datetime(date_string: str | None) -> datetime | None:
     """
-    parse a datetime string and return a timezone aware datetime object
+    parse a datetime string and return a timezone aware datetime object.
+
+    Returns `None` if no datetime string is given.
     """
+
+    if date_string is None:
+        return None
+
     try:
         parsed_datetime = datetime.strptime(date_string, "%Y-%m-%d %H:%M:%S")
     except ValueError:
@@ -48,18 +54,29 @@ def parse_datetime(date_string: str) -> datetime:
     )
 
 
-def parse_date(date_string: str) -> date:
+def parse_date(date_string: str | None) -> date | None:
     """
-    parse a date string and return a date object
+    parse a date string and return a date object.
+
+    Returns `None` if no date string is given.
     """
+
+    if date_string is None:
+        return None
+
     return datetime.strptime(date_string, "%Y-%m-%d").date()
 
 
-def parse_time(date_string: str) -> time:
+def parse_time(date_string: str | None) -> time | None:
     """
-    parse a time string and return a time object
+    parse a time string and return a time object.
+
+    Returns `None` if no time string is given.
     """
 
+    if date_string is None:
+        return None
+
     if len(date_string) == 5:
         return datetime.strptime(date_string, "%H:%M").time()
     else: