Calling an object of class in another class - php

Question

I am a newbie to OOP. I have worked in procedural programming a lot. So i am in little trouble right now. Can you please tell me how to call an object of a class in another class and then i can access all the variables and function of that class with using that object.
For e.g
I have a class of DBconnection. i write my db queries in it. Now i have an other class named Users. Now i need to access the db queries in User class, definitely i need object of DBconnection class to access all db queries. What can i do please help
The example code which i have written is as below:
**DBConnection class**
class DBConnection
{
public $SITEURL;
public $servername;
public $username;
public $password;
public $dbname;
public $objDbConnect;
function DBConnection(){
$this->SITEURL=Configuration::SITEURL;
$this->servername=Configuration::servername;
$this->username=Configuration::username;
$this->password=Configuration::password;
$this->objDbConnect=mysql_connect($this->servername,$this->username,$this->password);
if($this->objDbConnect){
mysql_select_db($this->dbname);
}
}
function InsertRecord($pStrTableName,$pArrField,$pArrValue)
{
$strSql="insert into $pStrTableName (";
$intFieldSize=count($pArrField);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.=$pArrField[$i];
}
else
{
$strSql.=$pArrField[$i].",";
}
}
$strSql.=") values (";
$intFieldSize=count($pArrValue);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.="'".$pArrValue[$i]."'";
}
else
{
$strSql.="'".$pArrValue[$i]."'".",";
}
}
$strSql.=")";
if(mysql_query($strSql))
{
return 1;
}
else
{
return 0;
}
}
}
**Users class**
class Users{
var $username,
$userpassword,
$email,
function User(){
}
}

Answer 1

The best way to do this would be to use Singleton pattern.
Following is an example
class DBConnection
{
private static $instance = null;
private function __construct() {
}
/*
* #return DBConnection
*/
public static function get_db()
{
if ( empty(self::$instance) ) self::$instance = new DBConnection();
return self::$instance;
}
public function query()
{
}
}
class User
{
function testfunc()
{
$db = DBConnection::get_db();
$db->query();
}
}

Answer 2

You can declare an object of your class in your second class and use it like
$c= new DBConnection();
$c->InsertRecord('Parameters here etc');
echo $c->username; //and other public variables similarly

Answer 3

DBConnection class
class DBConnection
{
public $SITEURL;
public $servername;
public $username;
public $password;
public $dbname;
public $objDbConnect;
function DBConnection(){
$this->SITEURL=Configuration::SITEURL;
$this->servername=Configuration::servername;
$this->username=Configuration::username;
$this->password=Configuration::password;
$this->objDbConnect=mysql_connect($this->servername,$this->username,$this->password);
if($this->objDbConnect){
mysql_select_db($this->dbname);
}
}
function InsertRecord($pStrTableName,$pArrField,$pArrValue)
{
$strSql="insert into $pStrTableName (";
$intFieldSize=count($pArrField);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.=$pArrField[$i];
}
else
{
$strSql.=$pArrField[$i].",";
}
}
$strSql.=") values (";
$intFieldSize=count($pArrValue);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.="'".$pArrValue[$i]."'";
}
else
{
$strSql.="'".$pArrValue[$i]."'".",";
}
}
$strSql.=")";
if(mysql_query($strSql))
{
return 1;
}
else
{
return 0;
}
}
}
Users class
class Users{
var $username;
var $userpassword;
var $email;
var $dbcon;
public function __construct()
{
//create an object
$this->dbconn = new DBConnection();
//get user name from dbconnection class
echo $this->dbconn->username;
}
function User(){
}
}
//create object for user class
$user = new User();

Answer 4

**DBConnection class**
class DBConnection
{
public $SITEURL;
public $servername;
public $username;
public $password;
public $dbname;
public $objDbConnect;
function DBConnection(){
$this->SITEURL=Configuration::SITEURL;
$this->servername=Configuration::servername;
$this->username=Configuration::username;
$this->password=Configuration::password;
$this->objDbConnect=mysql_connect($this->servername,$this->username,$this->password);
if($this->objDbConnect){
mysql_select_db($this->dbname);
}
}
public static function getConnection(){
if(!empty($this)){
return $this;
}
return new DBConnection();
}
function InsertRecord($pStrTableName,$pArrField,$pArrValue)
{
$strSql="insert into $pStrTableName (";
$intFieldSize=count($pArrField);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.=$pArrField[$i];
}
else
{
$strSql.=$pArrField[$i].",";
}
}
$strSql.=") values (";
$intFieldSize=count($pArrValue);
for($i=0;$i<$intFieldSize;$i++)
{
if($i==$intFieldSize-1)
{
$strSql.="'".$pArrValue[$i]."'";
}
else
{
$strSql.="'".$pArrValue[$i]."'".",";
}
}
$strSql.=")";
if(mysql_query($strSql))
{
return 1;
}
else
{
return 0;
}
}
}
**Users class**
class Users{
var $username,
$userpassword,
$email,
function User(){
$db = DBConnection::getConnection();
$db->InsertRecord($x, $x, $x);
}
}

Answer 5

1 . You can change your class DBConnection to singleton. And call your class in User like this DBConnection::getInstance()->InsertRecord(...). It's easy. But not recommended.
2 . You can push your DBConnection instance inside User. Like this
class Users{
var $db_connection;
function __construct($db_connection){
$this->db_connection = $db_connection;
}
$db_connection = new DBConnection(...);
$user = new User($db_connection);
3 . You can instantiate new DBCOnnection inside User class. Like in #Sundar answer.
P.S. Do not use old construct style.

Answer 6

You can keep a reference to the DBConnection in your User class (pass it in in the constructor).
private $dbConn;
function __contruct($dbConnRef) {
$this->dbConn = $dbConnRef;
}
public function storeSelf() {
$this->dbConn->InsertRecord(...);
}