Customize errors

FailedValidationTrait.php

<?php

namespace App\Http\Requests\Traits;

use Illuminate\Http\JsonResponse;
use Illuminate\Http\Exceptions\HttpResponseException;
use Illuminate\Contracts\Validation\Validator;
use Illuminate\Validation\ValidationException;

trait FailedValidationTrait 
{
    /**
     * Handle a failed validation attempt.
     *
     * @param  \Illuminate\Contracts\Validation\Validator  $validator
     * @return void
     *
     * @throws \Illuminate\Validation\ValidationException
     */
    protected function failedValidation(Validator $validator)
    {
        $response = [ 
            'invalid_fields' => []
        ];

        $errors = (new ValidationException($validator))->errors();

        foreach($errors as $field => $error){
            $response['invalid_fields'][$field] = $error[0];
        }

        throw new HttpResponseException(response()->json($response, JsonResponse::HTTP_UNPROCESSABLE_ENTITY));
    }
}