Stuck with CI4 Build Your First Application tutorial

They are in manual -> model.html#saving-data :

Code:

 
// Defined as a model property
$primaryKey = 'id';

// Does an insert()
$data = [
            'title' => $this->request->getPost('title'),
            'slug'  => url_title($this->request->getPost('title'), '-', true),
            'body'  => $this->request->getPost('body'),
        ];

$model->save($data);

// Performs an update, since the primary key, 'id', is found.
 $data = [
             'id' => $this->request->getPost('post_id'),
            'title' => $this->request->getPost('title'),
            'slug'  => url_title($this->request->getPost('title'), '-', true),
            'body'  => $this->request->getPost('body'),
        ];
$model->save($data);

Another Option:

Code:

$id_post = $this->request->getPost('post_id');
$data = [
            'title' => $this->request->getPost('title'),
            'slug'  => url_title($this->request->getPost('title'), '-', true),
            'body'  => $this->request->getPost('body'),
        ];
$model->insert($data);

$model->update($id_post,$data);