v2.29.0 introduced a bug with serialization that uses a wrapped serializer

[ornariece]

import pydantic


class MyModel(pydantic.RootModel):
    root: str

    @pydantic.model_serializer(mode="wrap")
    def my_wrapper_serializer(self, serializer: pydantic.SerializerFunctionWrapHandler):
        return "my_prefix:" + serializer(self)


class MyParentModel(pydantic.BaseModel):
    nested: MyModel

    @pydantic.field_serializer('nested', mode="wrap")
    def wrapped_field_serializer(
        self, field_value, serializer: pydantic.SerializerFunctionWrapHandler
    ):
        return serializer(field_value)


if __name__ == "__main__":
    my_model = MyParentModel.model_validate({'nested': "validated_value"})

    print(my_model.model_dump())
    #>expected: {'nested': 'my_prefix:validated_value'}
    #>actual:   {'nested': 'my_prefix:my_prefix:validated_value'}

i've narrowed down the issue to the "bump to pydantic-core 2.29.0" commit in pydantic.

taking a quick look at what changed in pydantic-core in that version, it seems the bug was introduced by this commit about memory optimization? it looks like the to_python method is naively delegating to the schema serializer without accounting for the wrapping mode. i know little about rust, and haven't really investigated so i could be far off here.

[Viicos]

Fixed by #1660.