[RESOLVED] OOPHP Newbie ! pls help me

TheStalker

Hi all,

I have been reading up on how OOPHP works and am trying to get into it but am finding very hard.

Today i have been trying to write my first ever class by myself, a mysql connect class. I thought this would be a good place to start. I am doing all my coding on my local machine running XAMPP.

ok so i thought i had it all down but no such luck, im getting the error

Warning: mysql_query() [function.mysql-query]: Access denied for user 'ODBC'@'localhost' (using password: NO) in C:\xampp\htdocs\index.php on line 11

Warning: mysql_query() [function.mysql-query]: A link to the server could not be established in C:\xampp\htdocs\imaddresses\index.php on line 11

When ive seen this before its norm been the username or password for mysql have been set wrong, but ive checked this in my code by hard coding them into the method.

here is my code

classLib.php

<?php
class mysqlCon{

var $host; 
var $username;
var $password;
var $dbName;
var $con;
var $selectDb;

function openDb(){

	require("includes/connectDb.php"); 
	$con =  mysql_connect($host,$username,$password);
	$selectDb = mysql_select_db($dbName, $con);

}

} 



?>

connectDb.php

<?php 

//Create new instance of the class mysqlCon
$con = new mysqlCon();
//set vars
$con->host = "localhost"; 
$con->username = "root";
$con->password = "password";
$con->dbName = "imaddresses";
//use the connect method here
$con->openDb();


?>

index.php

<?php include("library/classLib.php"); ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>test</title>
</head>

<body>
<?php
$sql = mysql_query("SELECT* FROM users");



?>

</body>
</html>

Maybe im doing sum thing real dumb, but an help would be great. Like i said this is my first ever class soooo go easy on my lol :queasy:

cheers

Shrike

In openDb you need to use the qualifier $this to refer to object variables, e.g. $this->host. You might also consider initialising the variables in the object constructor.

TheStalker

i have tried using $this-> but still get teh same error. Am i doing this right ? also if possible could you give an example of what mean about the object constructor.

thanks

function openDb(){

	require("includes/connectDb.php"); 
	$con =  mysql_connect($this->host,$this->username,$this->password);
	$selectDb = mysql_select_db($this->dbName, $this->con);


}

NogDog

function openDb(){

    require("includes/connectDb.php");
    [color=red]$this->[/color]con =  mysql_connect($this->host,$this->username,$this->password);
    $selectDb = mysql_select_db($this->dbName, $this->con);


}

TheStalker

NogDog;10957001 wrote:

function openDb(){

    require("includes/connectDb.php");
    [color=red]$this->[/color]con =  mysql_connect($this->host,$this->username,$this->password);
    $selectDb = mysql_select_db($this->dbName, $this->con);


}

Thanks for your reply, ive tried the above and still the same error :bemused:

bradmasterx

<?php
class mysqlCon{

var $hostname;
var $username;
var $password;
var $dbName;
var $con;

function __construct(){
    $this->hostname = "localhost";
    $this->username = "root";
    $this->password = "password";
    $this->dbName = "imaddresses";
    $this->con = 0;
    $this->openDb();
}

function openDb(){

    $this->con =  mysql_connect($this->hostname,$this->username,$this->password);
    $selectDb = mysql_select_db($this->dbName, $this->con);

}

}



?>

This should work 😛

NogDog

Looking back at the original post, it appears you never actually instantiate the class, so the db connection is never performed.

TheStalker

Ok so ive got this to work now, with a little help from you all ! So thank you very much for all your replys, i am determined to learn OOPHP but am finding it very foreign to the PHP im used to.

This is what i now have

classLib

<?php
class mysqlCon{

var $hostname;
var $username;
var $password;
var $dbName;
var $con;



function openDb(){
     require("includes/ConnectDb.php");
    $this->con =  mysql_connect($this->hostname,$this->username,$this->password);
    $selectDb = mysql_select_db($this->dbName, $this->con);

}


}



?>

connectDb

<?php 
//set vars
$this->host = "localhost"; 
$this->username = "root";
$this->password = "password";
$this->dbName = "imaddresses";

?>

index

<?php include("library/classLib.php"); ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<title>test</title>
</head>

<body>
<?php

$con = new mysqlCon();
$con->openDb();


$sql = mysql_query("SELECT* FROM users");


?>

</body>
</html>

Ok so i have some questions for you all on bits that im not understanding.

Can someone explain to me what $this-> does ? Does it just set vars that you have declared?
what does the object constructor do and why do you need it ? As you see above ive not used it, just because im not really sure what its doin ?
Is there a way so include $con = new mysqlCon(); and $con->openDb(); in the method so i dont have to call it at the start of every page to open my database? i.e i can just include the classLib and my database connection will be active.

thanks for all your help, hope those questions dont sound too dumb :queasy:

NogDog

$this basically means "this object", i.e. the currently instantiated object under which this method is being executed. It differentiates what follows the arrow as being an object member, as opposed to something local in scope to that function (method).

class Test
{
   private $foo = 3;
   public function example()
   {
      $foo = 55; // local to this function
      echo $foo; // 55
      echo $this->foo; // 3
   }
}

The constructor method is automatically executed when the object in instantiated. So to answer your 3rd question, just change the name of that method to construct() to make it happen automatically when you create the object, or you can leave it separate if desired and create a constructor that calls it:

   public function __construct()
   {
      $this->openDb();
   }

PS: From an object-oriented design standpoint, I'm not crazy about including a hard-coded file name within that method, as that creates a strong dependency upon the application's environment and configuration, reducing re-usability and the goal of loose coupling of objects.

TheStalker

NogDog;10957163 wrote:
$this basically means "this object", i.e. the currently instantiated object under which this method is being executed. It differentiates what follows the arrow as being an object member, as opposed to something local in scope to that function (method).
class Test
{
   private $foo = 3;
   public function example()
   {
      $foo = 55; // local to this function
      echo $foo; // 55
      echo $this->foo; // 3
   }
}
The constructor method is automatically executed when the object in instantiated. So to answer your 3rd question, just change the name of that method to construct() to make it happen automatically when you create the object, or you can leave it separate if desired and create a constructor that calls it:
   public function __construct()
   {
      $this->openDb();
   }
PS: From an object-oriented design standpoint, I'm not crazy about including a hard-coded file name within that method, as that creates a strong dependency upon the application's environment and configuration, reducing re-usability and the goal of loose coupling of objects.

Thank you very much for getting back to me soon fast. I think im going to have to keep at it till it sinks in a bit more. I think i userstand a bit more from your answers, so thank you.

i might also take into account your surgestion and add the vars for the connect into the method itself.

As a starting point i guess this is a good class 🆒