Using external variables in classes

Question

I have a directory structure:

app
cofig
 config.php
classes
 db.class.php
index.php

config.php:

<?php

define('DB_HOST', 'localhost'); 
define('DB_USER', 'root'); 
define('DB_PASS', ''); 
define('DB_NAME', 'db_name');

db.class.php:

<?php 
include "config/config.php";

class DB {

private $conn;
private $results;

public function __construct() {

$this->conn = mysql_connect(DB_HOST, DB_USER, DB_PASS);//**This doesn't work**
mysql_select_db(DB_NAME, $this->conn);
}

}
?>

when I try to create an instance of the $db class in index.php, I get errors (cannot obtain DEFINED variables in class)

This should work .... are you sure you have `require_once()`'d config.php ? — Eugen Rieck, Jun 05 '12 at 17:30
are you using the wrong config file or is it just a type o? you have imported db.config but defined vars in config.php — dm03514, Jun 05 '12 at 17:30

score 3 · Answer 1 · answered Jun 05 '12 at 17:41

Having this directory structure:

app
config
 config.php
classes
 db.class.php
index.php

will force you to use: include('../config/config.php'); or define an absolute PATH that goes to the root and do: include(PATH.'config/config.php');.

Your include "config/config.php"; is interpreted as include('root/classes/config/config.php') which, I assume, doesn't exists.

You should anyway pass, as Samy suggested, constants to the class via constructor so that you can use the same class for multiple connection with different database variables.

And also, it is not suggested to use mysql or mysqli function anymore. Learn about PDO.

You're right, but including isn't the fix, I still cannot get defined DB_ variables from the db class — mpet, Jun 05 '12 at 17:44

score 2 · Answer 2 · answered Jun 05 '12 at 17:41

2

Assuming that "cofig" in your directory structure is a typo, use:

include("../config/config.php");

answered Jun 05 '12 at 17:41

Scott Saunders

29,840
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Ok, even fixing that, it cannot access DB_HOST, DB_PASS etc from the class – mpet Jun 05 '12 at 17:42
Yes I can, before class definition. But cannot access them from within the db class – mpet Jun 05 '12 at 17:45
1

Move the include line within your constructor. – Scott Saunders Jun 05 '12 at 17:48
Did that fix the problem? If so, you can mark this answer correct so that others know the problem is solved. – Scott Saunders Jun 05 '12 at 18:07
Unfortunately it was not the cause; the real cause was putting comment right behind the opening – mpet Jun 05 '12 at 18:36

score 2 · Answer 3 · answered Jun 05 '12 at 17:44

According to your directory structure include path should be '../config/config.php'. Since you are using include, it does not throw fatal error and continue code execution whther file is included or not. Here your file is not included as per the code. Try this

  <?php 
include "../config/config.php";

class DB {

    private $conn;
    private $results;

    public function __construct() {

        $this->conn = mysql_connect(DB_HOST, DB_USER, DB_PASS);//**This doesn't work**
        mysql_select_db(DB_NAME, $this->conn);
     }

 }
?>

Samy Dindane · Answer 4 · 2012-06-05T17:41:21.080

1

Pass these variables to your class as parameters, it's cleaner anyway.

class DB {
    public function __construct($host, $dbName, $user, $password) {
        $this->conn = mysql_connect($host, $user, $password);
        mysql_select_db($dbName, $this->conn);
    }
}

new DB(DB_HOST, DB_NAME, DB_USER, DB_PASS);

By the way, mysql_ functions are in the process of being deprecated.

edited Jun 05 '12 at 17:41

answered Jun 05 '12 at 17:31

Samy Dindane

17,900
3
40
50

1

"By the way, mysql_ functions are deprecated." Useful comment – mpet Jun 05 '12 at 17:36
What do you recommend instead? PDO.. or..? – mpet Jun 05 '12 at 17:37
PDO or mysqli, though [PDO is probably better.](http://stackoverflow.com/questions/10696696/which-one-is-faster-and-lighter-mysqli-pdo) – Jeroen Jun 05 '12 at 17:39
PHP recommend *mysqli* or PDO (http://www.php.net/manual/en/intro.mysql.php). -- I'd say PDO... or an ORM. :) – Samy Dindane Jun 05 '12 at 17:39
Did you mean for this function in the first place? http://php.net/manual/en/function.mysql-db-query.php it has been deprecated as of 5.3.0. I think that mysql_connect, mysql_query still exist – mpet Jun 05 '12 at 17:40

Using external variables in classes

4 Answers4