Unable to serialize objects returned by custom resolvers in parameters

[ravi-kumar-pilla]

Description

Originally raised by Erwin - https://kedro-org.slack.com/archives/C03RKP2LW64/p1722343503669499

Context

From the user -

I just discovered that if I use a custom resolver in parameters, (using it in catalog have no problem) kedro-viz die. The object returned is not friendly for kedro-viz

"polars": lambda x: getattr(pl, x)

pydantic_core._pydantic_core.PydanticSerializationError: Unable to serialize unknown type: <class 'polars.datatypes.classes.DataTypeClass'>
2024-07-30 09:15:55,489 - uvicorn.error - ERROR - Exception in ASGI application

Any workaround? Could be a bad practice to have parameters of type polars.datatypes.classes.DataTypeClass ?

Steps to Reproduce

Let's say we have the below resolver -

"custom_resolvers": {
        "add": lambda *my_list: sum(my_list),
        "polars": lambda x: getattr(pl, x)
    }

If the parameters have a resolver and used as below -

model_options:
  test_size: "${add:1,2,3}"
  random_state: 3
  data_info: "${polars:Float64}"

Kedro Viz constructs an object like -

parameters={
    'model_options': {
      'test_size': 6,
      'random_state': 3,
      'data_info': Float64,
}

Now Float64 is not serializable by pydantic when it is sent as json to frontend. We either need to make str(Float64) or see what to do in case the parameter value is an object.

Expected Result

Kedro-Viz should handle parameter values of object types and do not crash

Actual Result

Kedro-Viz throws and error and does not start.

pydantic_core._pydantic_core.PydanticSerializationError: Unable to serialize unknown type: <class 'polars.datatypes.classes.DataTypeClass'>
2024-07-30 09:15:55,489 - uvicorn.error - ERROR - Exception in ASGI application

Your Environment

Include as many relevant details as possible about the environment you experienced the bug in:

• Web browser system and version: Chrome
• Operating system and version: macOS
• NodeJS version used (if relevant):
• Kedro version used (if relevant): latest
• Python version used (if relevant):

Checklist

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[ravi-kumar-pilla]

Possible implementations -
Using - https://docs.pydantic.dev/latest/api/functional_serializers/#pydantic.functional_serializers.field_serializer
and handling the parameters_value in ParametersNode at models/flowchart.py