Function to make datetime from separate date & time fields (#76)

adtl/transformations.py

@@ -148,3 +148,26 @@ def makeDateTimeFromSeconds(date, time_seconds, date_format, tzname):
     hour = time_seconds // 3600
     minute = (time_seconds % 3600) // 60
     return t.replace(hour=hour, minute=minute).isoformat()
+
+
+def makeDateTime(date, time_24hr, date_format, timezone):
+    """Combine date and time fields into one"""
+    if date == "":
+        return None
+
+    try:
+        dt = datetime.strptime(date, date_format).replace(
+            tzinfo=zoneinfo.ZoneInfo(timezone)
+        )
+    except ValueError:
+        logging.error(
+            f"Could not convert date {date!r} from date format {date_format!r}"
+        )
+        return None
+
+    if time_24hr == "":
+        return dt.date().isoformat()  # return date only
+
+    tm = datetime.strptime(time_24hr, "%H:%M").time()
+
+    return datetime.combine(dt, tm, tzinfo=zoneinfo.ZoneInfo(timezone)).isoformat()

tests/test_transformations.py

@@ -145,3 +145,19 @@ def test_makeDateTimeFromSeconds(date, time_seconds, date_format, tzname, expect
 )
 def test_textIfNotNull(field, return_text, expected):
     assert transform.textIfNotNull(field, return_text) == expected
+
+
+@pytest.mark.parametrize(
+    "date,time,date_format,tzname,expected",
+    [
+        ("", "00:00", "%d/%m/%Y", "UTC", None),
+        ("04/05/2020", "10:00", "%d/%m/%Y", "UTC", "2020-05-04T10:00:00+00:00"),
+        ("04/05/2020", "", "%d/%m/%Y", "UTC", "2020-05-04"),
+        ("04/05/2020", "", "%m/%d/%Y", "UTC", "2020-04-05"),
+        ("04/05/2020", "", "%Y-%m-%d", "UTC", None),
+        ("05/06/2020", "16:00", "%d/%m/%Y", "UTC", "2020-06-05T16:00:00+00:00"),
+        ("05/06/2020", "16:00", "%d/%m/%Y", "Asia/Tokyo", "2020-06-05T16:00:00+09:00"),
+    ],
+)
+def test_makeDateTime(date, time, date_format, tzname, expected):
+    assert transform.makeDateTime(date, time, date_format, tzname) == expected