I need to validate a field which cannot be true if another field is greater than 0

services.*.not_taxable could be resolved by some lookup rules, maybe an accessor. I guess I don't understand the validation here.

Accessor was just example, you could write a helper class that returns whats needed.

$somevar  = 'taxable' === true ? Helper::return something : $somevar;

Just example. But if I had several situations, I'd probably reach for some helper functions.

@nicolaferrara82

Create a custom rule, loop over the services array and have it return false if it encounters the condition of vat > 0 and not_taxable !== false

Something like:

 'services.*.not_taxable' => [
	'sometimes:required',
	'boolean',
	new NonTaxable
]

namespace App\Rules;

use Illuminate\Contracts\Validation\Rule;

class NonTaxable implements Rule
{

    public function passes($attribute, $value) : bool
    {

		return 
			$service['vat'] == 0 ||
 			($service['vat'] > 0 && $service['not_taxable'] === false);

    }

}

I think that would work, I've never tried it for arrays.. it should pass each element of the array into the rule object for validation.

If it doesn't work for some reason, then this might:

 'services' => [new NonTaxable]

    public function passes($attribute, $services) : bool
    {

	return ! $services->reject(function ($service) {
		return 
			$service['vat'] == 0 ||
 			($service['vat'] > 0 && $service['not_taxable'] === true);
	})->count();

    }

Basically passes the entire array into the rule object, if a service doesn't pass the truth test, it will remain within the collection. So if the count is greater than 0, the passes() method will return false and the validation will fail. I wouldn't reach for this unless the first example doesn't work.

I obviously haven't test, so you might need to fiddle around with it, but hopefully gives you an idea on how to tackle the validation.

@nicolaferrara82 Does using services.* not work?

I just realized I had an error in my first snippet:

'services.*' => [new NonTaxable]

If you can make that work, I would think it would then include an array of errors including the keys?

I remember having to do something like this once, where I came up with a very hacky solution. I think I resorted to just manually inserting the keys into the array returned from the FormRequest's messages() method.

Upon every failed element, I'd add it to an array, then merge it with the FormRequest's message() array.

// in the loop, keep track of every failed element - pseduo code:

$services->reject(function ($service, $key) {

	if ($logicFails) {
		$this->nonTaxableFailures["not_taxable.{$key}"] = "Taxes required with VAT"; 
	}
});

then merge it within the rules():

    public function messages()
    {
    
        return $this->nonTaxableFailures + [
            'someotherrule' => 'some other message',
            'someotherrule2' => 'some other message2'
        ];
    
    }

Then I just had to make sure I handled the errors on the front end.

There might be an easier way.. my situation was very complex. I'm still surprised if just passing in the array doesn't automatically provide you the formatted errors for free?