Dataclasses bug: Encoding includes unspecified instance attributes

When encoding a dataclass, instance attributes that aren’t dataclass-fields are included in the result:

import dataclasses
import msgspec


@dataclasses.dataclass
class Foo:
    id: int


foo = Foo(id=1)
foo.bar = "test"


print(msgspec.json.encode(foo))
print(msgspec.json.encode(dataclasses.asdict(foo)))

assert msgspec.json.encode(foo) == msgspec.json.encode(dataclasses.asdict(foo))

This is problematic because it differs from dataclasses.asdict, and in turn makes mgspec incompatible with pydantic.dataclasses:

from dataclasses import asdict

import msgspec
from pydantic.dataclasses import dataclass


@dataclass
class Foo:
    id: int


foo = Foo(id=1)


print(msgspec.json.encode(foo))
print(msgspec.json.encode(asdict(foo)))

[provinzkraut]

Mmk. Should be a quick fix; expect a patch release in the next day or two.

Perfect, thanks a lot!

If you have time, could you check if there are any other incompatibilities so we can batch them all in one release?

I just ran our test suites against the latest release and this was the only thing that popped up. Nothing else comes to mind at the moment, but should I come across anything else I’ll let you know!

[jcrist]

Mmk. Should be a quick fix; expect a patch release in the next day or two. If you have time, could you check if there are any other incompatibilities so we can batch them all in one release?