How to check if variable is not defined?

[kenorb]

E.g. when workflow is called externally, inputs variable is defined (e.g. ${{ inputs.foo }}). However when running workflow on the local repository, then inputs aren't defined.

How to check if inputs are not defined?

E.g.

  my-job:
    if: ${{ inputs is undefined }}

I think I can do something like: if: ${{ github.event.inputs.someinput == '' }}, but I don't think it's a good idea (as I need to hardcoded some input name). Is there another way?