Fix parameters missing from services (#381)

src/betterproto/__init__.py

@@ -379,15 +379,10 @@ def _preprocess_single(proto_type: str, wraps: str, value: Any) -> bytes:
     elif proto_type == TYPE_MESSAGE:
         if isinstance(value, datetime):
             # Convert the `datetime` to a timestamp message.
-            seconds = int(value.timestamp())
-            nanos = int(value.microsecond * 1e3)
-            value = _Timestamp(seconds=seconds, nanos=nanos)
+            value = _Timestamp.from_datetime(value)
         elif isinstance(value, timedelta):
             # Convert the `timedelta` to a duration message.
-            total_ms = value // timedelta(microseconds=1)
-            seconds = int(total_ms / 1e6)
-            nanos = int((total_ms % 1e6) * 1e3)
-            value = _Duration(seconds=seconds, nanos=nanos)
+            value = _Duration.from_timedelta(value)
         elif wraps:
             if value is None:
                 return b""
@@ -1505,6 +1500,15 @@ from .lib.google.protobuf import (  # noqa
 
 
 class _Duration(Duration):
+    @classmethod
+    def from_timedelta(
+        cls, delta: timedelta, *, _1_microsecond: timedelta = timedelta(microseconds=1)
+    ) -> "_Duration":
+        total_ms = delta // _1_microsecond
+        seconds = int(total_ms / 1e6)
+        nanos = int((total_ms % 1e6) * 1e3)
+        return cls(seconds, nanos)
+
     def to_timedelta(self) -> timedelta:
         return timedelta(seconds=self.seconds, microseconds=self.nanos / 1e3)
 
@@ -1518,6 +1522,12 @@ class _Duration(Duration):
 
 
 class _Timestamp(Timestamp):
+    @classmethod
+    def from_datetime(cls, dt: datetime) -> "_Timestamp":
+        seconds = int(dt.timestamp())
+        nanos = int(dt.microsecond * 1e3)
+        return cls(seconds, nanos)
+
     def to_datetime(self) -> datetime:
         ts = self.seconds + (self.nanos / 1e9)
         return datetime.fromtimestamp(ts, tz=timezone.utc)