from typing import Annotated, Any, TypeVar
from typing import Annotated, Any
from pydantic import BaseModel, WrapValidator, WrapSerializer, WithJsonSchema
from pydantic_core import PydanticOmit
from pydantic_core.core_schema import SerializerFunctionWrapHandler, ValidatorFunctionWrapHandler

def _ser_missing(v: Any, handler: SerializerFunctionWrapHandler) -> Any:
    if v is Missing:
        raise PydanticOmit
    return handler(v)

def _val_missing(v: Any, handler: ValidatorFunctionWrapHandler) -> Any:
    if v is Missing:
        return v
    return handler(v)

T = TypeVar('T')

MaybeMissing = Annotated[T, WrapValidator(_val_missing), WrapSerializer(_ser_missing), WithJsonSchema({'type': []})]

Missing: MaybeMissing[Any] = object()  # type: ignore


class Model(BaseModel):
    y: int
    x: MaybeMissing[int] = Missing

print(Model.model_json_schema())
print(Model(y=1).model_dump())
print(Model(y=1, x=2).model_dump())