Typing - accessing children of a `Sequence` element

[paperflo]

Hi @b4rtaz,

I have a use case that's quite similar to the triggers example. As in that example, the first step in the root sequence is the launch pad. I am restricting it further such that only one trigger can be added, which functionally works well. To make the typing work I'm currently using a type assertion, because the sequence property isn't defined on the elements of Sequence.

const configuration: DesignerConfiguration = {
  placeholder: {
    canShow(
      sequence: Sequence,
      _index: number,
      _draggingStepComponentType: string,
      draggingStepType: string,
      definition: Definition
    ) {
      const launchPad = definition.sequence[0] as SequentialStep // here

      const isTriggerStep = draggingStepType === 'trigger'
      const isLaunchPadSequence = sequence === launchPad.sequence // to make this access possible
      const triggerExists = launchPad.sequence.length > 0 // and this one

      return (
        (isTriggerStep && isLaunchPadSequence && !triggerExists) ||
        (!isTriggerStep && !isLaunchPadSequence)
      )
    },
  },

  ...otherConfig,
}

Is there a way to make the typing work without the type assertion, something I've missed maybe?

[b4rtaz]

Hello, yes, for now you need to cast (as SequentialStep). It’s a known typing limitation and will be improved in a future version.

[paperflo]

@b4rtaz Alright, got it. Thanks for the quick reply, and for developing the whole project! It's pretty powerful 💪

[b4rtaz]

Let’s keep this open until it’s resolved.