Add total seconds float support to the TimeDelta field

Able to (de)serialise to float values as a representation of the total seconds.

AUTHORS.rst

@@ -169,3 +169,4 @@ Contributors (chronological)
 - Kevin Kirsche `@kkirsche <https://github.com/kkirsche>`_
 - Isira Seneviratne `@Isira-Seneviratne <https://github.com/Isira-Seneviratne>`_
 - Karthikeyan Singaravelan `@tirkarthi  <https://github.com/tirkarthi>`_
+- Marco Satti `@marcosatti  <https://github.com/marcosatti>`_

src/marshmallow/fields.py

@@ -1434,17 +1434,24 @@ def _make_object_from_format(value, data_format):
 
 class TimeDelta(Field):
     """A field that (de)serializes a :class:`datetime.timedelta` object to an
-    integer and vice versa. The integer can represent the number of days,
-    seconds or microseconds.
+    integer or float and vice versa. The integer or float can represent the
+    number of days, seconds or microseconds (for integers) or the total seconds
+    (for floats).
 
-    :param precision: Influences how the integer is interpreted during
+    :param precision: Influences how the integer or float is interpreted during
         (de)serialization. Must be 'days', 'seconds', 'microseconds',
-        'milliseconds', 'minutes', 'hours' or 'weeks'.
+        'milliseconds', 'minutes', 'hours', 'weeks' or 'total_seconds'.
+        The 'total_seconds' precision interprets values as floats.
+        Other precisions will be interpreted as integers.
+        When using the `total_seconds` precision mode, data precision loss
+        may occur.
     :param kwargs: The same keyword arguments that :class:`Field` receives.
 
     .. versionchanged:: 2.0.0
         Always serializes to an integer value to avoid rounding errors.
         Add `precision` parameter.
+    .. versionchanged:: 3.17.0
+        Allow (de)serialization to float as the value of total seconds.
     """
 
     DAYS = "days"
@@ -1454,6 +1461,7 @@ class TimeDelta(Field):
     MINUTES = "minutes"
     HOURS = "hours"
     WEEKS = "weeks"
+    TOTAL_SECONDS = "total_seconds"
 
     #: Default error messages.
     default_error_messages = {
@@ -1471,6 +1479,7 @@ def __init__(self, precision: str = SECONDS, **kwargs):
             self.MINUTES,
             self.HOURS,
             self.WEEKS,
+            self.TOTAL_SECONDS,
         )
 
         if precision not in units:
@@ -1485,18 +1494,28 @@ def __init__(self, precision: str = SECONDS, **kwargs):
     def _serialize(self, value, attr, obj, **kwargs):
         if value is None:
             return None
+        if self.precision == self.TOTAL_SECONDS:
+            return value.total_seconds()
         base_unit = dt.timedelta(**{self.precision: 1})
         delta = utils.timedelta_to_microseconds(value)
         unit = utils.timedelta_to_microseconds(base_unit)
         return delta // unit
 
     def _deserialize(self, value, attr, data, **kwargs):
+        if self.precision == self.TOTAL_SECONDS:
+            deser_type = float
+        else:
+            deser_type = int
+
         try:
-            value = int(value)
+            value = deser_type(value)
         except (TypeError, ValueError) as error:
             raise self.make_error("invalid") from error
 
-        kwargs = {self.precision: value}
+        if self.precision == self.TOTAL_SECONDS:
+            kwargs = {"seconds": value}
+        else:
+            kwargs = {self.precision: value}
 
         try:
             return dt.timedelta(**kwargs)

tests/test_deserialization.py

@@ -692,6 +692,12 @@ def test_timedelta_field_deserialization(self):
         assert result.seconds == 123
         assert result.microseconds == 456000
 
+        total_seconds_value = 322.223
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        result = field.deserialize(total_seconds_value)
+        assert isinstance(result, dt.timedelta)
+        assert result.total_seconds() == total_seconds_value
+
     @pytest.mark.parametrize("in_value", ["", "badvalue", [], 9999999999])
     def test_invalid_timedelta_field_deserialization(self, in_value):
         field = fields.TimeDelta(fields.TimeDelta.DAYS)

tests/test_serialization.py

@@ -658,34 +658,44 @@ def test_timedelta_field(self, user):
         assert field.serialize("d1", user) == 86401000001
         field = fields.TimeDelta(fields.TimeDelta.HOURS)
         assert field.serialize("d1", user) == 24
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d1", user) == user.d1.total_seconds()
 
         field = fields.TimeDelta(fields.TimeDelta.DAYS)
         assert field.serialize("d2", user) == 1
         field = fields.TimeDelta(fields.TimeDelta.SECONDS)
         assert field.serialize("d2", user) == 86401
         field = fields.TimeDelta(fields.TimeDelta.MICROSECONDS)
         assert field.serialize("d2", user) == 86401000001
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d2", user) == user.d2.total_seconds()
 
         field = fields.TimeDelta(fields.TimeDelta.DAYS)
         assert field.serialize("d3", user) == 1
         field = fields.TimeDelta(fields.TimeDelta.SECONDS)
         assert field.serialize("d3", user) == 86401
         field = fields.TimeDelta(fields.TimeDelta.MICROSECONDS)
         assert field.serialize("d3", user) == 86401000001
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d3", user) == user.d3.total_seconds()
 
         field = fields.TimeDelta(fields.TimeDelta.DAYS)
         assert field.serialize("d4", user) == 0
         field = fields.TimeDelta(fields.TimeDelta.SECONDS)
         assert field.serialize("d4", user) == 0
         field = fields.TimeDelta(fields.TimeDelta.MICROSECONDS)
         assert field.serialize("d4", user) == 0
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d4", user) == user.d4.total_seconds()
 
         field = fields.TimeDelta(fields.TimeDelta.DAYS)
         assert field.serialize("d5", user) == -1
         field = fields.TimeDelta(fields.TimeDelta.SECONDS)
         assert field.serialize("d5", user) == -86400
         field = fields.TimeDelta(fields.TimeDelta.MICROSECONDS)
         assert field.serialize("d5", user) == -86400000000
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d5", user) == user.d5.total_seconds()
 
         field = fields.TimeDelta(fields.TimeDelta.WEEKS)
         assert field.serialize("d6", user) == 1
@@ -708,6 +718,8 @@ def test_timedelta_field(self, user):
         assert field.serialize("d6", user) == d6_seconds * 1000 + 1
         field = fields.TimeDelta(fields.TimeDelta.MICROSECONDS)
         assert field.serialize("d6", user) == d6_seconds * 10**6 + 1000 + 1
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        assert field.serialize("d6", user) == user.d6.total_seconds()
 
         user.d7 = None
         assert field.serialize("d7", user) is None
@@ -721,6 +733,19 @@ def test_timedelta_field(self, user):
         field = fields.TimeDelta(fields.TimeDelta.SECONDS)
         assert field.serialize("d9", user) == 1
 
+        user.d10 = dt.timedelta(
+            weeks=1,
+            days=6,
+            hours=2,
+            minutes=5,
+            seconds=51,
+            milliseconds=10,
+            microseconds=742,
+        )
+        field = fields.TimeDelta(fields.TimeDelta.TOTAL_SECONDS)
+        # Test for reasonable approximate equality. No guarantees are made about accuracy.
+        assert abs(field.serialize("d10", user) - 1130751.010742) < 0.1
+
     def test_datetime_list_field(self):
         obj = DateTimeList([dt.datetime.utcnow(), dt.datetime.now()])
         field = fields.List(fields.DateTime)