pass a PDO db object instance to other class function

Question

I have an PDO object in an included file and when i use it in main page it works great. And when i pass it into an object to use it inside of them it simply dont work.

I've tried directly and with reference (function xxxx(&dbd){ this->$db = &dbd }), simply dont work, but if i pass another type of value (as a string) that works perfect. If i send a $db = "olaola" it works but if it is an PDO it fails. I'm a newbie in php and in english, so be patient please :P

included file:

$username = "root";
$password = "*****";
$host = "localhost";
$dbname = "dbname";
$db = NULL;
$options = array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8');

try
{
    $db = new PDO("mysql:host={$host};dbname={$dbname};charset=utf8", $username, $password, $options);
}
catch(PDOException $ex)
{
    die("Failed to connect to the database: " . $ex->getMessage());
}

$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);

in main:

$pagMenu = new pages($db);

in pages class:

class pages {

    private $db;

    function __construct($db) { 
        $this->$db = $db;
    }
}

What does "doesn't work" mean exactly? What does or doesn't it do? — deceze
– deceze ♦, Commented Nov 2, 2012 at 16:04
how do you access the $db object in your class pages? (you cant access it from outside because its private in your example) — Vengarioth
– Vengarioth, Commented Nov 2, 2012 at 16:05
Using $this->db in the pages class should have the same results as using $db in the main program. — Diego Saa
– Diego Saa, Commented Nov 2, 2012 at 17:31

deceze · Accepted Answer · 2012-11-02 16:04:50Z

6

The syntax is:

    $this->db = $db;

Not $this->$db.

answered Nov 2, 2012 at 16:04

deceze♦

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3 Comments

user1726343 Over a year ago

Well spotted. Do you know why it was working with the string?

deceze Over a year ago

Because a string resolves to a proper "variable variable", or rather "variable property" here. An object is not a valid variable name.

user1726343 Over a year ago

You should put that in the answer too.

Diego Saa · Accepted Answer · 2012-11-02 16:28:38Z

5

You should do

$this->db = $db;

instead of

$this->$db = $db;

The second form is a variable variable, which means that you are assigning the value of the parameter to a variable named as the content of the variable, which will return an error if that content is a PDO object.

edited Nov 2, 2012 at 16:28

answered Nov 2, 2012 at 16:07

Diego Saa

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2 Comments

CondeGil Over a year ago

Tks a lot. By the way, do you know why i can use de db object in main but when i use it in "pages" class won't work? The fetchAll of resulting query in pages function return an array empty and in main result with the values.

Diego Saa Over a year ago

Using the $db object in main should give the same results as using $this->db in the pages class, because they are the same thing. Not sure what the error could be.

Mehmet Ali Kuş · Accepted Answer · 2019-01-28 03:05:04Z

0

Static syntax

$self::$variableName

This syntax

$this->variableName

answered Jan 28, 2019 at 3:05

Mehmet Ali Kuş

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