Custom Model in Codeigniter 4

I am looking for exactly the same. It is a pity there is no example for CI 4 in the documentation

Sorry, but it was off topic (I misread it).

If it was helpful for anybody, I restore it here now

How it works in my project:

• install CI4 via composer
• install GCE 3 via composer (see manual)
• configure app/Config/GroceryCrudEnterprise.php
• configure db connection in CI4

Then put

in app/Libraries/ the file GroceryCrudStarter.php:

<?php

namespace App\Libraries;

use GroceryCrud\Core\GroceryCrud;

class GroceryCrudStarter extends GroceryCrud
{
    public function __construct()
    {
        $config = (new \Config\GroceryCrudEnterprise())->getDefaultConfig();
        parent::__construct($config, $this->getDbData());
    }

    private function getDbData()
    {
        $db = (new \Config\Database())->default;
        return [
            'adapter' => [
            'driver' => 'Pdo_Mysql',
            'host'     => $db['hostname'],
            'database' => $db['database'],
            'username' => $db['username'],
            'password' => $db['password'],
            'charset' => 'utf8'
            ]
        ];
    }
}

in app/Controllers/ the file ExampleController.php:

<?php

namespace App\Controllers;

use App\Libraries\GroceryCrudStarter;

class ExampleController extends BaseController
{
    public function manage()
    {
        $crud = new GroceryCrudStarter();
        $crud->unsetDeleteMultiple();
        $crud->setTable('example');
        $crud->setSubject('Example', 'Examples');
        $crud->columns(['name', 'info', 'updated_at', 'created_at']);
        $crud->fields(['name', 'info']);
        $crud->uniqueFields(['name']);

        $crud->setRule('name', 'required');

        $output = $crud->render();

        if ($output->isJSONResponse) {
            header('Content-Type: application/json; charset=utf-8');
            echo $output->output;
            exit;
        }

        return view('crud_general', (array)$output);
    }
}

(the table “example” must exists in db):

CREATE TABLE `example` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(100) NOT NULL,
  `info` varchar(200) DEFAULT NULL,
  `updated_at` datetime DEFAULT current_timestamp() ON UPDATE current_timestamp(),
  `created_at` datetime DEFAULT current_timestamp(),
  PRIMARY KEY (`id`),
  UNIQUE KEY `name` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_general_ci;

in app/Models/ the file ExampleModel.php:

<?php

namespace App\Models;

use CodeIgniter\Model;

class ExampleModel extends Model
{
    protected $DBGroup          = 'default';
    protected $table            = 'example';
    protected $primaryKey       = 'id';
    protected $useAutoIncrement = true;
    protected $insertID         = 0;
    protected $returnType       = 'array';
    protected $useSoftDeletes   = false;
    protected $protectFields    = true;
    protected $allowedFields    = ['name', 'info'];

    // Dates
    protected $useTimestamps = false;
    protected $dateFormat    = 'datetime';
    protected $createdField  = 'created_at';
    protected $updatedField  = 'updated_at';
    //protected $deletedField  = 'deleted_at';

    // Validation
    protected $validationRules      = [];
    protected $validationMessages   = [];
    protected $skipValidation       = false;
    protected $cleanValidationRules = true;

    // Callbacks
    protected $allowCallbacks = true;
    protected $beforeInsert   = [];
    protected $afterInsert    = [];
    protected $beforeUpdate   = [];
    protected $afterUpdate    = [];
    protected $beforeFind     = [];
    protected $afterFind      = [];
    protected $beforeDelete   = [];
    protected $afterDelete    = [];
}

in app/Views/ the file crud_general.php:

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
<?php
foreach ($css_files as $file) : ?>
    <link type="text/css" rel="stylesheet" href="<?php echo $file; ?>" />
<?php endforeach; ?>
<link type="text/css" rel="stylesheet" href="<?php echo base_url('assets/common/css/grocery_crud_form.css') ?>">
</head>
<body>
    <div>
          <a href='<?php echo site_url('example/manage')?>'>example</a>
    </div>
    <div style='height:20px;'></div>  
    <div style="padding: 10px">
        <?php echo $output; ?>
    </div>
    <?php foreach ($js_files as $file) : ?>
        <script src="<?php echo $file; ?>"></script>
    <?php endforeach; ?>
</body>
</html>

NOW,
you call in your Browser the URL http://your-webadress/example/manage
(f.ex. http://localhost:8080/example/manage, if you use the internal CI4 webserver with “sparc serve” for development)
and… vuala!