How to validate POST and non-POST data in Codeigniter 4

This is just a snippet of code so that I can refer back in the future if required.

How do you validate non-POST dan POST data in Codeigniter 4 without resorting to creating your own validation rules?

Let say we have a very simple form with one input:

<input type="text" name="item">

And we also have a data set acquired from somewhere else:

$data['price']= "5"

The key is to have our validation runs with a variable:

$validation->run($post)

First we set $post to combine both our POST and non-POST data:

$post = array_merge($request->getPost(), $data);

Then we run our validation script as required:

\\ set our validation rules
$validation->setRules([
    'item' => 'required',
    'price' => 'greater_than[0]'
]);

if(! $this->validation->run($post)) {
// error
} else {
// success
}

Hope this helps.