Desdroid opened a new issue, #56736: URL: https://github.com/apache/airflow/issues/56736
### Apache Airflow version 3.1.0 ### If "Other Airflow 2/3 version" selected, which one? _No response_ ### What happened? 3.1. changed quite a bit on the SerDe side. Now there is an own SerDe implementation for pydantic models. Here: https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/serialization/serializers/pydantic.py The implementation unfortunately doesn't serialize with mode='json' See: https://docs.pydantic.dev/latest/api/base_model/#pydantic.BaseModel.model_dump As an effect, Pydantic models which are more complex and have fields that have classes can no longer be JSON serialized, breaking XCOM serialization to json. The fix should be fairly simple though, just adding `mode='json'` to the serializer here https://github.com/apache/airflow/blob/main/airflow-core/src/airflow/serialization/serializers/pydantic.py#L49 should fix this. I haven't been able to set up the airflow repo myself to test it thoug. Additionally, using pydantic dataclasses is now broken as well, but I will create a separate issue for that. ### What you think should happen instead? _No response_ ### How to reproduce Add this dag to your Airflow instance: ```python from airflow.sdk import dag, task from datetime import datetime, timedelta from pydantic import BaseModel, AnyUrl from pipelines.dags.shared.dag_args import local_tz class UnserializableModel(BaseModel): foo: str bar: AnyUrl @dag( dag_id="pydantic_serde", dag_display_name="Pydantic Serialization Errors", schedule=timedelta(seconds=30), start_date=datetime(2025, 6, 27, 0, 0, 0, tzinfo=local_tz), catchup=False, description="1.0.0", ) def pydantic_serde() -> None: @task def return_pydantic_model(): return UnserializableModel(foo="hello", bar="https://example.com";) @task def consume_pydantic_model(model: UnserializableModel): print(model) consume_pydantic_model(return_pydantic_model()) pydantic_serde() ``` ### Operating System debian ### Versions of Apache Airflow Providers _No response_ ### Deployment Official Apache Airflow Helm Chart ### Deployment details _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) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
