How to write validation rule with resource in Laravel?

Question

I use Laravel 8 with Resource to define routes in api.php and DestroyProductRequest in my controller:

Route::resources([
    'product' => ProductController::class,
]);

In the controller:

public function destroy(DestroyProductRequest $request, Product $product) {
    $product->delete();

    return Response::HTTP_OK;
}

In the DestroyProductRequest.php:

public function rules() {
    return [
        'id' => 'required|integer|exists:products,id',
    ];
}

Now the key is the Route::resource convert the incoming id from the url into a model. But now how can I write the correct rule in the the rules() function?

Now it sais id: ["The id field is required."] in the error response.

Any idea?

Answer 1

By default Laravel does not validate the route parameters. You have add custom logic in order to work

public function rules()
{
    return [
        'product' => 'required|integer|exists:products,id',
    ];
}

protected function validationData()
{
    // Add the Route parameters to you data under validation
    return array_merge($this->all(),$this->route()->parameters());
}

In a normal use case, you wouldn't validate route request. Laravel would return a 404 Not Found exception. Which is a standard and appropriate response.