PHP mysqli connection class - cannot access the connection variable from outside. Scope of application
I am new to using PHP in OOP but ran into an issue with my database connection class.
I have a file with this mysqli connection class here
$db_name = 'dbname';
$db_user = 'dbuser';
$db_password = 'dbpassword';
$db_host = 'localhost';
class database {
public $mysqli;
public function connect($db_host, $db_user, $db_password, $db_name){
$this->mysqli = new mysqli($db_host, $db_user, $db_password, $db_name);
if ($mysqli->connect_errno) {
return "Sorry Andre, but you seem to have messed up the DB connection :(";
}
}
}
$newConnection = new database;
$newConnection->connect($db_host, $db_user, $db_password, $db_name);
Then I want to use the $ mysqli variable in the db connection in another file - this is a simple insert into the database using the $ mysqli variable to connect. I have included the above in the connection file, but it seems that the $ mysqli variable is not returned when I call the method on the database class. I am getting PHP error ...
Fatal error: Call to a member function prepare() on a non-object in...
I saw that using
global $mysqli;
works, however I want to do it properly, as I heard it is not good practice.
I realize that I am potentially doing things a little wrong here as I am new to using OOP, but I assumed that by returning this variable in the connect function, I could access it from creating the class outside.
Help rate, thanks.
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When used externally, you access the class variable through an instance ...
$newConnection = new database;
$newConnection->connect($db_host, $db_user, $db_password, $db_name);
$newConnection->mysqli /* here you have access from outside */
internally you are using the $ this keyword ...
// like this from inside
if ($this->mysqli->connect_errno) {
return "Sorry Andre, but you seem to have messed up the DB connection :(";
}
If you want to protect your variable from external access use:
private $mysqli;
// instead of
public $mysqli;
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Fatal error: Call to a member function prepare() on a non-object in...
This always means that the thing you called the on method is not an object. In your case: mysqli is not initializing.
general advice: connect looks like something that should be inside a constructor.
class d {
public function __construct($db_host, $db_user, $db_password, $db_name){
$this->mysqli = new mysqli($db_host, $db_user, $db_password, $db_name);
if ($this->mysqli->connect_errno) {
return "Sorry Andre, but you seem to have messed up the DB connection :(";
}
}
public $mysqli;
}
$foo = new d('host', 'user', 'pass', 'dbname');
$foo->mysqli->prepare("something");
So when you acquire an instance of this class, it is automatically initialized. Also this way you save the string every time you want to initialize it.
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