Implement new Bytes field

Author: rrad5409

src/marshmallow/fields.py

@@ -878,6 +878,44 @@ def _deserialize(self, value, attr, data, **kwargs) -> str:
             raise self.make_error("invalid_utf8") from error
 
 
+class Bytes(Field[bytes]):
+  """
+  Marshmallow field type for any bytes array.
+  """
+
+  def _deserialize(
+    self,
+    value: typing.Any,
+    attr: str | None,
+    data: typing.Mapping[str, typing.Any] | None,
+    **kwargs: typing.Any,
+  ) -> bytes:
+    try:
+      match value:
+        case bytes() as b:
+          return b
+        case bytearray() as ba:
+          return bytes(ba)
+        case str() as s:
+          return bytes(
+            s,
+            encoding="utf-8",
+            errors="ignore",
+          )
+        case int() as i:
+          return i.to_bytes(
+            length=max(1, (7 + i.bit_length()) // 8),
+            byteorder="big",
+            signed=i < 0,
+          )
+        case obj:
+          if isinstance(obj, (typing.SupportsBytes, typing.Iterable)):
+            return bytes(obj)
+      raise ValidationError("not a bytes-like object")
+    except TypeError as e:
+      raise ValidationError("not a bytes-like object") from e
+
+
 class UUID(Field[uuid.UUID]):
     """A UUID field."""
 

tests/test_deserialization.py

@@ -322,6 +322,23 @@ def test_string_field_deserialization(self):
         with pytest.raises(ValidationError):
             field.deserialize({})
 
+    def test_bytes_field_deserialization(self):
+        field = fields.Bytes()
+        assert field.deserialize(b"foo") == b"foo"
+        assert field.deserialize(bytearray(b"foo")) == b"foo"
+        assert field.deserialize("foo") == b"foo"
+        assert field.deserialize(0xDEAD) == b"\xDE\xAD"
+        assert field.deserialize([0xBE, 0xEF]) == b"\xBE\xEF"
+        assert field.deserialize((0xB, 0xA, 0xB, 0xE)) == b"\x0B\x0A\x0B\x0E"
+
+        with pytest.raises(ValidationError) as excinfo:
+            field.deserialize({"hi": 222})
+        assert excinfo.value.args[0] == "not a bytes-like object"
+
+        with pytest.raises(ValidationError) as excinfo:
+            field.deserialize(['12345'])
+        assert excinfo.value.args[0] == "not a bytes-like object"
+
     def test_boolean_field_deserialization(self):
         field = fields.Boolean()
         assert field.deserialize(True) is True