Function _pick_mapper

libs/langgraph/langgraph/graph/state.py:1718–1725

(
    state_keys: Sequence[str], schema: type[Any]
)

def _pick_mapper(
    state_keys: Sequence[str], schema: type[Any]
) -> Callable[[Any], Any] | None:
    if state_keys == ["__root__"]:
        return None
    if isclass(schema) and (issubclass(schema, BaseModel) or is_dataclass(schema)):
        return partial(_coerce_state, schema)
    return None


_S = TypeVar("_S")