How to create validation Rule Object, that is dependent on other field(s)

[aedart]

I recently struggled with a problem where I needed to create a custom validation rule, that was dependent on another field's value, for a nested data structure. Unfortunately, the documentation is not very clear how developers can create custom validation rule objects that are dependent on other fields, if at all possible?

The following illustrates the desired "semantic" I was trying to achieve:

use Illuminate\Support\Facades\Validator;

Validator::make([], [
    'records' => 'array|filled',
    'records.*.field_a' => 'required|string',
    'records.*.field_b' => [
        'required',
        new MyCustomRule('records.*.field_a') // Custom rule, dependent on "records.[index].field_a" value
    ]
]);

I have searched various forums, issues, laracast, ...etc, without any success. I ended up having to use the addDependentExtensions() method to add a custom rule. While it worked in my case, I do wonder how the "correct" way of creating dependent rule objects is?

Does anyone have a good example of how the above shown example can be achieved?

[henzeb]

In the docs I read someting about the DataAwareRule interface. See
https://laravel.com/docs/9.x/validation#using-rule-objects

[aedart]

Hi @henzeb
Yes, that is true. However, the documentation does not mention anything about how you obtain the correct index of current nested row / data-set that is being processed by the validation rule. It grants you all submitted data, as far as I can see when reviewing the code - or did I miss something?

[benounnas]

any updates? i faced the same issue unfortunately 😞

[aedart]

Sadly, not yet... still no clue how to do this correctly :(

[israaraujo]

Don't know if there is a "correct way". I used Closure.

If your attribute is part of an array you gonna get the index on the second position for example:

'items.*.foo' => 'required'
'items.*.baz' => [
        function (string $attribute, mixed $value, Closure $fail) {
            $index = explode('.', $attribute)[0];
            //lets say this is a Livewire 3 Form that has public $items as the array where you keep the items form data
            if ($this->items[$index]['foo'] == 'bar') {
                $fail("baz is invalid because foo is equals to bar.");
            }
        },
]

[OllieCrook]

Hello! Myself and @Ross2609 just came across this problem!

After lots of source code diving, this can be accomplished with Validator::extendDependent()

This means that when the validator processes the rule and reaches Validator.php Line 524 your rule name will be added to the $dependentRules array on Line 203 allowing the function that makes all of this possible replaceAsterisksInParameters to run!