[BUG] Tasks and workflows with default pydantic models cannot be launched from pyflyte.

[Tom-Newton]

Describe the bug

The to_click_option used in the pyflyte CLI cannot convert a pydantic.BaseModel default value to a click compatible default. This causes an error when trying to run any task or workflow that takes a pydantic.BaseModel from CLI arguments. @dataclass by comparison works fine.

import pydantic
from flytekit import task, workflow


class Model(pydantic.BaseModel):
    value: int


DEFAULT_MODEL = Model(value=1)


@task
def print_model(model: Model = DEFAULT_MODEL):
    print(model)


@workflow
def print_model_workflow(model: Model = DEFAULT_MODEL):
    print_model(model=model)

$ pyflyte run test_pydantic_cli.py print_model_workflow
UnserializableField: Field "" of type Model in __root__ is not serializable
$ pyflyte run test_pydantic_cli.py print_model
UnserializableField: Field "" of type Model in __root__ is not serializable

The problem is the same when running locally and remotely.

Expected behavior

I would expect the default pydantic.BaseModels to work without error like defaults of other types.

Thoughts on the solution

I can make pydantic.BaseModel work with a simple change

diff --git a/flytekit/clis/sdk_in_container/run.py b/flytekit/clis/sdk_in_container/run.py
index 7d661c3ff..3eb04e278 100644
--- a/flytekit/clis/sdk_in_container/run.py
+++ b/flytekit/clis/sdk_in_container/run.py
@@ -475,8 +475,9 @@ def to_click_option(
                 If no custom logic exists, fall back to json.dumps.
             """
             with FlyteContextManager.with_context(flyte_ctx.new_builder()):
-                encoder = JSONEncoder(python_type)
-                default_val = encoder.encode(default_val)
+                default_val = default_val.json()
         if literal_var.type.metadata:
             description_extra = f": {json.dumps(literal_var.type.metadata)}"

I guess we just need some logic here to so that both @dataclass and pydantic.BaseModel can be serialised to JSON.

Screenshots

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes

[Future-Outlier]

this is fixed here:
flyteorg/flytekit#3013

please try the release.
v1.15.0b1

[Future-Outlier]

thank you!

[Tom-Newton]

Thanks for the fix 🙌