Method append

lib/sqlalchemy/orm/attributes.py:1882–1904

(
        self,
        state: InstanceState[Any],
        dict_: _InstanceDict,
        value: Any,
        initiator: Optional[AttributeEventToken],
        passive: PassiveFlag = PASSIVE_OFF,
    )

        return adapter, collection

    def append(
        self,
        state: InstanceState[Any],
        dict_: _InstanceDict,
        value: Any,
        initiator: Optional[AttributeEventToken],
        passive: PassiveFlag = PASSIVE_OFF,
    ) -> None:
        collection = self.get_collection(
            state, dict_, user_data=None, passive=passive
        )
        if collection is PASSIVE_NO_RESULT:
            value = self.fire_append_event(
                state, dict_, value, initiator, key=NO_KEY
            )
            assert (
                self.key not in dict_
            ), "Collection was loaded during event handling."
            state._get_pending_mutation(self.key).append(value)
        else:
            if TYPE_CHECKING:
                assert isinstance(collection, CollectionAdapter)
            collection.append_with_event(value, initiator)

    def remove(
        self,