Constructing message from dictionary fails in protobuf 5.28.0 when message has a nested duration #518
Description
As of protobuf 5.28.0, there is a bug in proto-plus where constructing a message from a dictionary fails when the message definition has a field of type google.protobuf.duration_pb2.Duration. Note this problem only exists when duration is in a nested message. See below:
class Foo(proto.Message):
another_field: duration_pb2.Duration = proto.Field(
proto.MESSAGE,
number=1,
message=duration_pb2.Duration,
)
# this works
Foo(another_field="300s")
class Bar(proto.Message):
some_field = proto.Field(proto.MESSAGE, number=1, message=Foo)
# this raises `AttributeError: Fail to convert to Duration. Expected a timedelta like object got str: 'str' object has no attribute 'seconds'`
bar = Bar({"some_field":{"another_field":"300s"}})
There is a change in the code path of message construction in proto-plus when using protobuf 5.28.0 and newer
In 5.27.5, we have
MessageMeta.__new__ → marshal.to_proto() → BaseMarshal.get_rule() → MessageRule.to_proto() → TypeError
where the exception is TypeError: Message must be initialized with a dict: _default_package.Foo raised at the location below`
In 5.28.0, we have
MessageMeta.__new__ → marshal.to_proto() → BaseMarshal.get_rule() → MessageRule.to_proto() → AttributeError
where the exception is AttributeError: Fail to convert to Duration. Expected a timedelta like object got str: 'str' object has no attribute 'seconds'
Technically, this is not a breaking change in protobuf as they simply raised a different error. Proto-plus expected TypeError but AttributeError was raised instead.
See the re-production below:
In protobuf 5.27.5, run the code below
def test_duration_write_string_nested():
class Foo(proto.Message):
another_field: duration_pb2.Duration = proto.Field(
proto.MESSAGE,
number=1,
message=duration_pb2.Duration,
)
class Bar(proto.Message):
some_field = proto.Field(proto.MESSAGE, number=1, message=Foo)
bar = Bar({"some_field":{"another_field":"300s"}})
assert isinstance(bar.some_field.another_field, timedelta)
assert isinstance(Bar.pb(bar).some_field.another_field, duration_pb2.Duration)
assert bar.some_field.another_field.seconds == 300
assert Bar.pb(bar).some_field.another_field.seconds== 300
You'll see TypeError: Message must be initialized with a dict: _default_package.Foo raised at the location below`
proto-plus-python/proto/marshal/rules/message.py
Lines 34 to 37 in c54b31d
In protobuf 5.27.5, the TypeError is caught, and then we successfully run the following code:
proto-plus-python/proto/marshal/rules/message.py
Lines 38 to 45 in c54b31d
In protobuf 5.28.0 and newer, you'll see AttributeError instead which is not caught in the code below and instead AttributeError is returned to the user
proto-plus-python/proto/marshal/rules/message.py
Lines 34 to 45 in c54b31d