add error to laravel validation

1//setup Validator and passing request data and rules
2$validator = \Validator::make(request()->all(), [
3    'due_date' => 'required',
4    'template' => 'required'
5]);
6
7//hook to add additional rules by calling the ->after method
8$validator->after(function ($validator) {
9	
10    if (request('event') == null) {
11    	//add custom error to the Validator
12        $validator->errors()->add('event', 'Please select an event');
13    }
14
15});
16
17//run validation which will redirect on failure
18$validator->validate();
19
20//https://dcblog.dev/laravel-adding-custom-validation-errors

1$messages = $validator->errors()->getMessages();
2var_dump($messages);
3