[8.x] Add prohibited_if and prohibited_unless validation rules

[jessarcher]

I've found myself needing these validation rules on a few occasions, where exclude_if and exclude_unless don't quite go far enough.

For example, in the project I'm currently working on, the following payload includes contradictory information that is not sufficient to just exclude. Instead we need an outright validation failure.

Validator::validate([
    'is_deceased' => false, 
    'date_of_death' => '2021-03-09'
], [
    'date_of_death' => 'prohibited_unless:is_deceased,true'
]);

Not sure if this is a common enough use-case to go into the framework, but hopefully it helps others 🙂

If this gets merged, I will follow up with a PR to laravel/docs and the language file in laravel/laravel.

[rodrigopedra]

I know both can be considered synonyms, but I find forbidden easier to remember.

Might be because it is more common on web-development jargon, and I am not a native English speaker.

Besides of that, nice addition, I wrote a custom Rule for a past project for that exact use-case.

[timacdonald]

I think both words make sense, but my only concern with forbidden is the association with the 403 Forbidden response, and that it could be possible for someone to think that the forbidden_if rule will cause a 403 if the conditions are not met.

[driesvints]

fail_if & fail_unless maybe?

[lk77]

In that case i think that you should have an accessor, not an actual field on the database

public function getIsDeceasedAttribute()
{
     return $this->date_of_death !== null
}

it avoid storing the same information twice, and having possible inconsistencies

[jessarcher]

In that case i think that you should have an accessor, not an actual field on the database

I would usually agree, but in this case there is a clinical requirement to be able to store both, with the date being optional as it may not be known.