Class Question

[N-Bomb(Nerd)]

Hi,

 

I want to connect to my database with mysqli at the start of my class and be able to use that connection throughout my class without reconnecting again. I'm still pretty new to classes, but I can't figure this out..

 

I tried doing this in the in the construct, but it didn't work:

$this->connection = new mysqli("localhost", "username", "password", "database");

How can I access my connection to the database anywhere in my class without reconnect? 

 

Thanks.

[Buddski]

What do you mean by "it didnt work"? did you get any errors at all?

[JAY6390]

create a var called $db in your class (like you did with the connection)

Then in your __construct() method put

 

$this->db = new mysqli(........) as you did

and then to query use

$this->db->query('SELECT * FROM blablah'); etc etc

[ignace]

Your constructor should never do real work only initialization logic:

 

class SomeClass {
    private $_db;
    public function __construct($value) { $this->_value = $value;/* <-- no work */ }
    public function getDb() {
        if (null === $this->_db) {
            $this->_db = new MySQLi(...);
        }
        return $this->_db;
    }
}

 

When you are programming remember to always lazy-load everything hold the creation of an object off until you absolutly need it.

[ToonMariner]

you need a singleton  or helper function...

 

helper

function getDB ()
{
if(!isset($conn))
{
  $conn = new mysqli("localhost", "username", "password", "database");
}
return $conn;
}
////

then anywhre in your code where you need database just:

$db = getDB();
$db->query("SELECT * FROM `foo`");
?>

singleton class...

<?php
class DBConn
{

static $instance;
private $_conn;

private function __construct()
{
  $this->conn = new mysqli("localhost", "username", "password", "database");
}

public static function getInstance()
{
  if ( !isset (self::$instance) }
  {
   self::$instance	=	new DBConn ( );
  }
  return self::$_instance
}
}

/////

then anywhere in your code:

$db = DBConn::getInstance;

$db->query("SELECT * FROM `bar`);
?>

 

there is an over head so in most cases you would probably lean toward the helper function method...

[ignace]

You should avoid using Singleton's as discussed here: http://www.phpfreaks.com/forums/index.php/topic,283313.msg1343157.html

[ToonMariner]

The singleton can be a very useful design pattern...

 

In terms of databases and where you may need a second database connection yes it will not be what you want...

 

To get round that you can use an array in the class that stores the connection string (host,username,passord,database) and when called again see if the current connection string already exists - if so return that connection if not open a new one and return that.