#3339 Bugfix: Pydantic deserialization for FlyteFile and FlyteDirectory Pull request opened by gverkes Fixes #6669 ## Tracking issue Closes flyteorg/flyte#6669 ## Why are the changes needed? When deserializing Pydantic models containing

FlyteFile

or

FlyteDirectory

fields using

model_validate()

, the deserialized objects were missing private attributes (

_remote_source

,

_downloader

, etc.). This caused an

AttributeError

when attempting to re-serialize these objects with

model_dump()

, breaking the serialize → deserialize → serialize cycle. This is a critical bug that prevents users from using FlyteFile/FlyteDirectory within Pydantic BaseModel classes in a normal way. ## What changes were proposed in this pull request? Added Pydantic model validators to both

FlyteFile

and

FlyteDirectory

classes that ensure private attributes are properly initialized during deserialization: 1. FlyteFile (

flytekit/types/file/file.py

): • Enhanced

deserialize_flyte_file

validator to check if private attributes exist • If missing, reconstructs the FlyteFile using

dict_to_flyte_file()

transformer • If attributes already exist (e.g., when passing already-constructed FlyteFile), returns as-is 2. FlyteDirectory (

flytekit/types/directory/types.py

): • Applied same fix to

deserialize_flyte_dir

validator • Uses

dict_to_flyte_directory()

to properly reconstruct the object ## How was this patch tested? Added two new unit tests in `test_pydantic_basemodel_transformer.py`: 1.

test_flytefile_pydantic_model_dump_validate_cycle

- Verifies FlyteFile can be serialized, deserialized, and re-serialized without errors 2.

test_flytedirectory_pydantic_model_dump_validate_cycle

- Same for FlyteDirectory ## Check all the applicable boxes • I updated the documentation accordingly. • All new and existing tests passed. • All commits are signed-off. https://bito.ai#summarystart| ### Summary by Bito This pull request fixes a critical bug in deserializing Pydantic models with FlyteFile and FlyteDirectory fields by adding model validators for private attributes. It ensures proper initialization during deserialization and includes new unit tests to validate the functionality of these enhancements. flyteorg/flytekit