DAG object has no attribute 'schedule' (Airflow 2.5.0) - airflow

Question

Using Airflow 2.5.0. I am using a subdag, but imports are working fine:
from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.operators.subdag import SubDagOperator
from subdags.subdag_downloads import subdag_downloads
from datetime import datetime
with DAG('group_dag', start_date=datetime(2022, 1, 1),
schedule='#daily', catchup=False) as dag:
args = {'start_date':dag.start_date,
'schedule':dag.schedule,
'catchup':dag.catchup}
downloads = SubDagOperator(
task_id="downloads",
subdag=subdag_downloads(dag.dag_id, "downloads", args)
)
This is the error I'm getting when trying to run the DAG in my CLI:
Traceback (most recent call last):
File "/home/airflow/.local/lib/python3.7/site-packages/airflow/models/dagbag.py", line 339, in parse
loader.exec_module(new_module)
File "<frozen importlib._bootstrap_external>", line 728, in exec_module
File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
File "/opt/airflow/dags/group_dag.py", line 12, in <module>
'schedule':dag.schedule,
AttributeError: 'DAG' object has no attribute 'schedule'
As you can see from the code above, I am defining schedule='#daily' when I instantiate with DAG() as dag, so why can't I access that argument by using dag.schedule?
NOTE: I can access the other arguments just fine, such as dag.catchup and dag.start_date. I can also access the schedule by using dag.schedule_interval, but this seems silly and doesn't sit well with me that I don't understand why we can't use dag.schedule when schedule= is the argument we defined.

Answer 1

I agree with Elad about migrating to TaskGroup where SubDagOperator will be removed in Airflow 3.
But currently, you can access your dag schedule by dag.schedule_interval:
from airflow import DAG
from airflow.operators.bash import BashOperator
from airflow.operators.subdag import SubDagOperator
from subdags.subdag_downloads import subdag_downloads
from datetime import datetime
with DAG('group_dag', start_date=datetime(2022, 1, 1),
schedule='#daily', catchup=False) as dag:
args = {'start_date':dag.start_date,
'schedule':dag.schedule_interval,
'catchup':dag.catchup}
downloads = SubDagOperator(
task_id="downloads",
subdag=subdag_downloads(dag.dag_id, "downloads", args)
)

Answer 2

You can't access it because there is no such parameter.
While you assign
DAG(..., schedule='#daily') as dag:
The DAG class does not have self.schedule. Airflow accept several kinds of scheduling options and creates from it an internal scheduling_args parameter. You can see it in the codebase here
I'd like to point that you are using SubDAG which is a deprecated feature for 2 years. Please migrate to TaskGroup. SubDAGs are not going to stay in Airflow 3.