Class _RelationshipArg

lib/sqlalchemy/orm/relationships.py:259–291

stores a user-defined parameter value that must be resolved and parsed later at mapper configuration time.

@dataclasses.dataclass
class _RelationshipArg(Generic[_T1, _T2]):
    """stores a user-defined parameter value that must be resolved and
    parsed later at mapper configuration time.

    """

    __slots__ = "name", "argument", "resolved"
    name: str
    argument: _T1
    resolved: Optional[_T2]

    def _is_populated(self) -> bool:
        return self.argument is not None

    def _resolve_against_registry(
        self, clsregistry_resolver: Callable[[str, bool], _class_resolver]
    ) -> None:
        attr_value = self.argument

        if isinstance(attr_value, str):
            self.resolved = clsregistry_resolver(
                attr_value, self.name == "secondary"
            )()
        elif callable(attr_value) and not _is_mapped_class(attr_value):
            self.resolved = attr_value()
        else:
            self.resolved = attr_value

    def effective_value(self) -> Any:
        if self.resolved is not None:
            return self.resolved
        else:
            return self.argument


_RelationshipOrderByArg = Union[Literal[False], Tuple[ColumnElement[Any], ...]]