About global mysql connection on CI 4

Hello there,

I was using CI 3, but today i downloaded version 4. I could not set $db variable global to use every function?

Anyone can give me example code ?

Thanks...

PHP Code:

<?php namespace App\Controllers;

ini_set('display_errors',1);
class Home extends BaseController
{
    public function __construct()
    {

        $db = \Config\Database::connect();
}
    public function index()
    {
        $query = $this->db->query('SELECT * FROM cats');
      $results = $query->getResult();
print_r($results);
$data = [];
    //    $data['cats'] = $results;
        return view('index');

    }


    //--------------------------------------------------------------------

} 


You are assigning $db and not $this->db. You should however set it in your BaseController.

PHP Code:

class BaseController extends Controller
{

    /**
     * An array of helpers to be loaded automatically upon
     * class instantiation. These helpers will be available
     * to all other controllers that extend BaseController.
     *
     * @var array
     */
    protected $helpers = [];

    /**
     * Constructor.
     */
    public function initController(\CodeIgniter\HTTP\RequestInterface $request, \CodeIgniter\HTTP\ResponseInterface $response, \Psr\Log\LoggerInterface $logger)
    {
        // Do Not Edit This Line
        parent::initController($request, $response, $logger);

        //--------------------------------------------------------------------
        // Preload any models, libraries, etc, here.
        //--------------------------------------------------------------------
        // E.g.:
        $this->db = \Config\Database::connect();
    }

} 


You are assigning $db and not $this->db. You should however set it in your BaseController.

PHP Code:

class BaseController extends Controller
{

    /**
     * An array of helpers to be loaded automatically upon
     * class instantiation. These helpers will be available
     * to all other controllers that extend BaseController.
     *
     * @var array
     */
    protected $helpers = [];

    /**
     * Constructor.
     */
    public function initController(\CodeIgniter\HTTP\RequestInterface $request, \CodeIgniter\HTTP\ResponseInterface $response, \Psr\Log\LoggerInterface $logger)
    {
        // Do Not Edit This Line
        parent::initController($request, $response, $logger);

        //--------------------------------------------------------------------
        // Preload any models, libraries, etc, here.
        //--------------------------------------------------------------------
        // E.g.:
        $this->db = \Config\Database::connect();
    }

} 


Thank you so much, it solved

It might be interesting to know that you can get a database connection instance anywhere without carrying it around in a base class property.

PHP Code:

$db = \Config\Database::connect(); 


Sets $db to the default connection group. If the instance exists it will be returned, otherwise, a new instance is created and returned.

Here's the signature for Database::connect() as found in /system/Database/Config.php

PHP Code:

public static function connect($group = null, bool $getShared = true)