Attach after-validation callback hooks inside Form Requests to execute custom multi-field checks after standard validation rules pass.
While standard validation rules handle type and constraint checks on individual attributes, complex cross-field business logic (such as checking account balances or verifying third-party inventory) often ends up cluttering controller methods.
Form Requests support the after() method to attach custom callbacks directly to the underlying validator.
Adding an after() Hook
Define an after() method returning an array of callables in your Form Request:
namespace App\Http\Requests;
use Illuminate\Foundation\Http\FormRequest;
use Illuminate\Validation\Validator;
class TransferFundsRequest extends FormRequest
{
public function rules(): array
{
return [
'recipient_id' => ['required', 'exists:users,id'],
'amount' => ['required', 'numeric', 'min:1'],
];
}
public function after(): array
{
return [
function (Validator $validator) {
// Runs only after standard rules pass
if ($this->user()->balance < $this->amount) {
$validator->errors()->add(
'amount',
'Insufficient account balance to complete this transfer.'
);
}
if ($this->user()->id === (int) $this->recipient_id) {
$validator->errors()->add(
'recipient_id',
'You cannot transfer funds to yourself.'
);
}
}
];
}
}Summary
- Executes after standard syntax and type rules pass successfully.
- Adds errors directly to the
$validator->errors()bag using standard form error keys. - Keeps controller methods clean and focused entirely on business fulfillment.
Tags:
Laravel Validation Form Requests Architecture