Home / Questions / 155595
Accepted
Yoel Rodriguez
Asked: 2020-04-14 07:42:01 +0800 CST 2020-04-14 07:42:01 +0800 CST

How to make my mysql connection in php usable in all classes

  • 772

I have the following situation: I have a class called primary to which I make an extension to a class called user. In the primary class, I call in a __construct in which I start a connection to mysql , I want to use that connection in my user class to avoid calling it in all my classes, which extends from the primary . I have declared a variable of type protected ($db) for the connection but what is happening to me is that when I try to access my connection from the extended class it sends me the following error:

Fatal error: Call to a member function query() on null in /opt/lampp/htdocs/pendientes/models/usuario_model.php on line 17

Primary Class:

class primary_model {

    protected $db;
    public $aplicacion;

    public function __construct() {
        $this->db = classDb::conexion();
        $this->aplicacion = array();
    }
}

User Class:

class usuario_model extends primary_model {

    public function get_usuarionum($search){
        $query = $this->db->query("select * from user WHERE 1 ".$search."");
        return mysqli_num_rows($query);
    }
}
php

1 Answers

  1. Best Answer

    I think you can solve it this way:

    Connection Class:

    Class Conexion{
 protected $db;

 public function __construct(){
  $this->db = new mysqli("localhost","root","","nombrebd");
 }

}

    This is your primary model class:

    require('ClassConexion.php');

Class primary_model{
  protected $db;
  public $aplicacion;

  public function __construct(){
   //Creamos el obj, instanciando la clase Conexion()
   $this->db = new Conexion();
   $this->aplicacion = array();
  }
}

    Already in the user class:

    require('ClassPrimary.php);

 Class usuario extends primary_model{

   public function __construct(){
     parent::__construct();
   }

   public function get_usuarionum($search){
     $query = $this->db->query("SELECT * FROM user WHERE 1 ".$search."");
     return mysqli_num_rows($query);
   }

 }

    That way you could do it, although in my personal opinion I would only use the connection class and it would extend it to the other classes that it is going to use, I also recommend using PDO and prepared statements.

    You can also just extend the Connection class in the user class and in the constructor access the parent::__construct();entire class you are inheriting in this way.

    • 1