azharizz opened a new issue, #70527:
URL: https://github.com/apache/airflow/issues/70527
### Under which category would you file this issue?
Airflow Core
### Apache Airflow version
Airflow 3.x
### What happened and how to reproduce it?
Serializing a `dateutil.relativedelta` that uses absolute time fields set to
`0` (e.g. `hour=0` for midnight) drops those fields. After the Dag is
deserialized, the schedule no longer snaps to midnight and keeps the base
datetime's clock time instead.
Root cause is in `encode_relativedelta`
(`airflow-core/src/airflow/serialization/encoders.py`):
```python
encoded = {k: v for k, v in var.__dict__.items() if not k.startswith("_")
and v}
```
The `and v` filter treats every falsy value as "unset". That is correct for
**relative** fields (`hours`, `days`, …), which default to `0`, but wrong for
**absolute** fields (`hour`, `minute`, `second`, `day`, …), which default to
`None`. For absolute fields, `0` is meaningful like e.g. `hour=0` means "snap
to midnight".
**Minimal repro:**
```python
from datetime import datetime
from dateutil.relativedelta import relativedelta, FR
from airflow.serialization.serialized_objects import BaseSerialization
delta = relativedelta(weekday=FR, hour=0, minute=0, second=0)
base = datetime(2024, 1, 10, 15, 30, 45)
print(base + delta)
# expected: 2024-01-12 00:00:00
round_tripped =
BaseSerialization.deserialize(BaseSerialization.serialize(delta))
print(base + round_tripped)
# actual today: 2024-01-12 15:30:45 (hour/minute/second lost)
```
Same bug hits any path that serializes intervals via `encode_relativedelta`
/ `encode_interval` (Dag schedules, timetables, serialized deltas).
Example Dag schedule that silently changes meaning after parse → serialize →
scheduler:
```python
from datetime import datetime
from dateutil.relativedelta import relativedelta, FR
from airflow.sdk import DAG
with DAG(
dag_id="example_friday_midnight",
start_date=datetime(2024, 1, 1),
schedule=relativedelta(weekday=FR, hour=0, minute=0, second=0),
catchup=False,
):
...
```
After serialization, the absolute `hour`/`minute`/`second` fields are gone,
so runs are planned at the previous interval's wall-clock time instead of
00:00:00.
### What you think should happen instead?
This is for the example:
Absolute fields with value `0` must survive the encode → decode round-trip.
Relative fields that are `0` can still be dropped (they mean "unset").
Expected encode for `relativedelta(weekday=FR, hour=0)`:
```python
{"hour": 0, "weekday": [4]}
```
not only `{"weekday": [4]}`.
### Operating System
Debian
### Deployment
Other
### Apache Airflow Provider(s)
_No response_
### Versions of Apache Airflow Providers
_No response_
### Official Helm Chart version
main (development)
### Kubernetes Version
_No response_
### Helm Chart configuration
_No response_
### Docker Image customizations
_No response_
### Anything else?
_No response_
### Are you willing to submit PR?
- [x] Yes I am willing to submit a PR!
### Code of Conduct
- [x] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
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