[I] Serialization of nested attr objects [airflow]

["tomrutter (via GitHub)" <gi...@apache.org>]

tomrutter opened a new issue, #38540:
URL: https://github.com/apache/airflow/issues/38540

   ### Apache Airflow version
   
   2.8.4
   
   ### If "Other Airflow 2 version" selected, which one?
   
   _No response_
   
   ### What happened?
   
   I am passing values between tasks using xcom. These values are instances of a attrs class that has another attrs class as a member. The serialisation currently fails to correctly mark the inner class with the __class__ tags to allow it to be deserialized back to the attrs class (it remains as a dict after loading into the downstream task).
   
   ### What you think should happen instead?
   
   I think that the nested attrs objects should be returned unchanged after deserialization.
   
   ### How to reproduce
   
   The value of `foo` passed to `task2` has the `inner_value` as a `dict` rather than a `InnerClass` instance.
   
   ```
   import attrs
   
   @attrs.define(kw_only=True, frozen=True, slots=False)
   class OuterClass:
     inner_value: InnerClass
   
   @attrs.define(kw_only=True, frozen=True, slots=False)
   class InnerClass:
     x: str
   
   
   @task
   def task1():
       return OuterClass(inner_value=InnerClass("test!")
   
   @task
   def task2(foo: OuterClass):
       print(foo)  # foo here is OuterClass(inner_value={"x": "test!"})
   
   @dag
   def my_dag():
       task2(task1())
   
   ```
   
   ### Operating System
   
   linux (standard airflow slim images extended with airflow providers running on kubernetes)
   
   ### Versions of Apache Airflow Providers
   
   defaults for 2.8.4
   
   ### Deployment
   
   Official Apache Airflow Helm Chart
   
   ### Deployment details
   
   Airflow deployment on Azure Kubernetes using postgres backend db.
   
   ### Anything else?
   
   I think a simple solution would be to update the following code in `airflow.serialization.serde.py` (lines 182 to 187), to change the value of `recurse` in the call to `attr.asdict` from `True` to `False`, leaving the serialization of inner classes to the subsequent call to `serialize`.
   
   Before:
   ```
       # attr annotated
       if attr.has(cls):
           # Only include attributes which we can pass back to the classes constructor
           data = attr.asdict(cast(attr.AttrsInstance, o), recurse=True, filter=lambda a, v: a.init)
           dct[DATA] = serialize(data, depth + 1)
           return dct
   ```
   
   After:
   ```
       # attr annotated
       if attr.has(cls):
           # Only include attributes which we can pass back to the classes constructor
           data = attr.asdict(cast(attr.AttrsInstance, o), recurse=False, filter=lambda a, v: a.init)
           dct[DATA] = serialize(data, depth + 1)
           return dct
   ```
   
   That is 
   
   ### 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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Re: [I] Serialization of nested attr objects [airflow]

["uranusjr (via GitHub)" <gi...@apache.org>]

uranusjr closed issue #38540: Serialization of nested attr objects
URL: https://github.com/apache/airflow/issues/38540


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