[frontend] optional pipeline parameters

[asaff1]

Environment

• How did you deploy Kubeflow Pipelines (KFP)?
  Standalone

• KFP version:
  2.1.0

Steps to reproduce

Create a pipeline component with Optional[int] parameter. The UI will still require it, even though in the component yaml it is marked as optional. See:

But UI shows:

Also probably related, when setting default value for integer type to 0, it shows blank. (so 0 for integer is considered as no default value).

Expected result

UI pipeline form should respect optional parameter

Materials and Reference

---

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[tumido]

+1, we're also impacted by this.

Simple reproducer here:

from typing import Optional
from kfp import compiler, dsl


@dsl.component()
def print_param_op(int_param: Optional[int] = None):
    print(int_param)

@dsl.pipeline()
def pipeline(int_param: Optional[int] = None):
    print_param_task = print_param_op(int_param=int_param)

if __name__ == "__main__":
    compiler.Compiler().compile(pipeline, "pipeline.yaml")

KFP DSL properly translates this to:

...
root:
  dag:
    tasks:
      print-param-op:
        cachingOptions:
          enableCache: true
        componentRef:
          name: comp-print-param-op
        inputs:
          parameters:
            int_param:
              componentInputParameter: int_param
        taskInfo:
          name: print-param-op
  inputDefinitions:
    parameters:
      int_param:
        isOptional: true
        parameterType: NUMBER_INTEGER
schemaVersion: 2.1.0
sdkVersion: kfp-2.10.1

However I'm unable to run the pipeline unless the param value is set.