Own validation rules with CodeIgniter >4.5

I would like to remind you that some people don't use anything: neither groups nor classes. They create them in controllers 

Yes and as I said, CodeIgniter gives you that freedom. This forum is for best practices and that's what the OP asked. What you consider a best practice may differ.

You are wrong about $this‐>validator, the object will appear only after validation, so you can’t work with it before that.

You're absolutely right about that, the could should be:

PHP Code:

if($this->validateData($data, 'newsletter'))
 $validatedData = $this->validator->getValidated(); 


The controller does instantiate it automatically, but only after you use one of the validation methods.

Halberd | CodeIgniter Sandbox