Add additional callbacks for wizard steps

[lukas-frey]

Issue

Currently, wizard steps only have a beforeValidation() and afterValidation() step.

However, in my case for example, I have a quite complex Wizard with conditional steps (I conditionally hide steps that are not needed, based on what the user has filled out in the previous steps).

This means, that I can not rely on the order of the steps: sometimes step 3 follows immediately after step 2, but if step 2 is hidden, step 3 follows immediately after step 1.

So in order to do something with the step (for example, prefill default data based on the previous steps), I have no way to achieve this.

If the data would not have been dependant on previous steps, I could use ->default() on the individual form fields.

If the steps would not be conditional (e.g. some being hidden depending on previous steps), I could have used afterValidation() to prepare the next step.

But in this case, I have no way to do that. In filament v3, the steps fired events like wizard::previous-step and wizard::next-step that I could hook into, but filament v4 removed that so I'm left with no solution in v4.

Proposal

So my proposal is to add additional callback functions in the Wizard's nextStep() function:

public function nextStep(int $currentStepIndex): void
{
    // Other code
    $currentStep->callAfterValidation();
    $nextStep->callBeforeFill(); // <- here
    $nextStep?->fillStateWithNull();
    $nextStep->callAfterFill(); // <- here
}

Or maybe something like fillUsing()/modifyFillUsing()... Just something that let's you hook into how the next step is initialized.

If this is okay @danharrin, I can create a PR.

[danharrin]

How about allowing you to inject a $nextStepSchema object in the existing beforeValidation() and afterValidation(), and then you can call $nextStepSchema->fill() on that?

[lukas-frey]

Yeah that would work too! Does fill currently also fill defaultState? For some reason I have a feeling that it did in v3, but I'm not sure and it does not seem to do that in v4.

[danharrin]

If you pass fill() without args, it fills the defaults, if you pass an array it fills with that data and not defaults. But injecting $nextStepSchema does not exist yet.

[lukas-frey]

Actually, now that I think of it:

Would it actually work? since after callAfterValidation(), $nextStep?->fillStateWithNull() is called, so it would still get overriden with nulls I think.

$currentStep->callBeforeValidation();
$currentStep->getChildSchema()->validate();
$currentStep->callAfterValidation();
$nextStep?->fillStateWithNull();

I guess we could provide a default afterValidation() implementation which would call $nextStepSchema->fillStateWithNull() and then we would just get rid of the $nextStep?->fillStateWithNull(); part.

So when you provide your own implementation, you either need to call fillStateWithNull again or do something else (such as just fill() in this case).

Similar how mountUsing for Actions works, where you also need to manually trigger the fill if you decide to implement mounting yourself.

[danharrin]

fillStateWithNull() doesn't actually overwrite existing state, it just fills in the gaps in state if new components have been added during that time.

[lukas-frey]

Ah okay, awesome.

In that case I can make a PR for it.