Failing a validation in a FormRequest withValidator method in Laravel

Question

I've created a custom FormRequest to validate requests relating to a particular product with attributes. One of the rules is, of course, that the request product field exists in the products database.

However, I have a more complicated rule that must be checked after. I'm checking this rule using the withValidator method, and then doing:

$validator->after(function ($validator) {
    // check the extra rule
    ...
});

(It doesn't particularly matter, but this rule is to check that, given the user selected attributes like color and size, this corresponds to a unique sku belonging to the product)

So how do I cause the validation to fail?

Another requirement is that when this validation fails, it should return a 500 instead of a 422. Additionally, it should return a custom JSON response if this sku is out of stock. How do I do this within FormRequest?

Answer 1

To add an error in an after hook you can do it like so:

$validator->after(function ($validator) {
    if (!$someCondition) {
        $validator->errors()->add('key', 'Some error message explaining error.');
    }
});

If you are validating the product field, then the 'key' should be 'product'.

For the second requirement you can override the failedValidation function.

protected function failedValidation(Validator $validator)
{
    throw (new ValidationException($validator))
                ->errorBag($this->errorBag)
                ->redirectTo($this->getRedirectUrl())
                ->status(500);
}

Now if you need to send a custom response, you could check for the 500 status in your App\Exceptions\Handler.php

public function render($request, Throwable $exception)
{
    if (is_a($exception, ValidationException::class) && $exception->getCode() === 500) {
        // Handle your custom JSON reponse
    }

    return parent::render($request, $exception);
}