Laravel - Validation - Adding After Hooks To Form Requests

If you would like to add an "after" validation hook to a form request, you may use the withValidator method. This method receives the fully constructed validator, allowing you to call any of its methods before the validation rules are actually evaluated:

     * Configure the validator instance.
     * @param  \Illuminate\Validation\Validator  $validator
     * @return void
    public function withValidator($validator)
        $validator->after(function ($validator) {
            if ($this->somethingElseIsInvalid()) {
                $validator->errors()->add('field', 'Something is wrong with this field!');