Disallow using an empty key in XCom pull

[vatsrahul1001]

Body

Currently we allow this pulled_value_1 = ti.xcom_pull(key="", task_ids="push"). We should not allow sending empty keys

pulled_value_1 = ti.xcom_pull(key=None, task_ids="push")

Eventually leads to:

    @staticmethod
    @provide_session
    def get_many(
        *,
        run_id: str,
        key: str | None = None,
        task_ids: str | Iterable[str] | None = None,
        dag_ids: str | Iterable[str] | None = None,
        map_indexes: int | Iterable[int] | None = None,
        include_prior_dates: bool = False,
        limit: int | None = None,
        session: Session = NEW_SESSION,
    ) -> Query:
        """
        Composes a query to get one or more XCom entries.

        This function returns an SQLAlchemy query of full XCom objects. If you
        just want one stored value, use :meth:`get_one` instead.

        :param run_id: DAG run ID for the task.
        :param key: A key for the XComs. If provided, only XComs with matching
            keys will be returned. Pass *None* (default) to remove the filter.

Here we see that a non empty value for "key" disables the filter (no where(XCom.key == key), it does not filter for None.

This is how it looks:

if key:
    query = query.filter(BaseXCom.key == key)

It really doesn't make any sense to have an xcom with "" as key.

Committer

• I acknowledge that I am a maintainer/committer of the Apache Airflow project.

[felipe-henao]

should this just be rejected or pull the return value from the push task?

[amoghrajesh]

@kiran2706 next time you are working on something, get the issue assigned to yourself so that the issue has an assignee and multiple people arent working on it

[kiran2706]

@amoghrajesh or @vatsrahul1001 - Could you please assign this issue to me?

[amoghrajesh]

Assigned to you