The "Custom field types" doc talks about a __bson__ method with an example that doesn't include it

[Terseus]

Bug

In the page about Custom field types we can see the following phrase at the start:

Sometimes, it might be required to customize as well the field BSON serialization. In order to do this, the field class will have to implement the __bson__ class method.

However the it does show this example that, as we can see, doesn't contains any method called __bson__, instead it uses the WithBsonSerializer annotation:

from typing import Annotated
from odmantic import AIOEngine, Model, WithBsonSerializer

class ASCIISerializedAsBinaryBase(str):
    @classmethod
    def __get_validators__(cls):
        yield cls.validate

    @classmethod
    def validate(cls, v):
        if isinstance(v, bytes):  # Handle data coming from MongoDB
            return v.decode("ascii")
        if not isinstance(v, str):
            raise TypeError("string required")
        if not v.isascii():
            raise ValueError("Only ascii characters are allowed")
        return v


def serialize_ascii_to_bytes(v: ASCIISerializedAsBinaryBase) -> bytes:
    # We can encode this string as ascii since it contains
    # only ascii characters
    bytes_ = v.encode("ascii")
    return bytes_


ASCIISerializedAsBinary = Annotated[
    ASCIISerializedAsBinaryBase, WithBsonSerializer(serialize_ascii_to_bytes)
]

class Example(Model):
    field: ASCIISerializedAsBinary

engine = AIOEngine()
await engine.save(Example(field="hello world"))
fetched = await engine.find_one(Example)
print(fetched.field)
#> hello world

Current Behavior

Go to https://art049.github.io/odmantic/fields/#custom-field-types and read the doc.

Expected behavior

The technique described in the doc and the one used in the example should match.

Environment

• ODMantic version: v1.0.1
• MongoDB version: N/A
• Pydantic infos (output of python -c "import pydantic.utils; print(pydantic.utils.version_info())): N/A
• Version of additional modules (if relevant): N/A