fatal error when extending simple class

Question

I have simple line class autorization extends mysql and it causes Fatal error: Call to a member function close() on a non-object in... On that line is

function __destruct(){
        $this->connection->close();
    }

Constructor

$mysqli = new mysqli(*****);
$this->connection = $mysqli;

at the moment no other methods ot class mysql are not used

Seems, that `$this->connection` is not an object (probably `null`), but without seeing, where you define it, or what you do with it in between, nobody can tell you _why_ — KingCrunch, Aug 08 '12 at 07:16
Where are you creating that instance of mysqli? In your auth class or your mysql class? And where is that destructor sitting? — , Aug 08 '12 at 07:23
IMO this `autorization` or `authorization` as its speelled has nothing todo with your database and thus should not extend your mysql class but instead have the databse connection passed to it. — Lawrence Cherone, Aug 08 '12 at 07:27
But `extends` usually means "is a", i.e. to a certain degree (the more the better) you should be able to put an instance of `autorization` where the code expects an instance of `mysql`. And given the names of the classes imho that's rather unlikely; therefore I agree with Lawrence. see also: https://en.wikipedia.org/wiki/Liskov_substitution_principle — VolkerK, Aug 08 '12 at 07:36
@LawrenceCherone thanks for authorization. The problem is that i cant directly access authorization (only from other class) — user1564141, Aug 08 '12 at 07:39
@VolkerK something wrong with my oop... As i see, the constructor runs automatically when object creates, so when i calling some methods from parent class - it works or not? — user1564141, Aug 08 '12 at 07:51
possible duplicate of [Call to a member function on a non-object](http://stackoverflow.com/questions/54566/call-to-a-member-function-on-a-non-object) — tereško, Feb 17 '13 at 12:14

score 1 · Accepted Answer · answered Aug 08 '12 at 07:43

1

Connection property is not initialised . If you have a constructor in mysql class make sure that you haven't completely overwritten it by specifying a constructor in autorization class. This can be achieved by adding:

parent::__constructor( any_params_to_mysql_go_here );

Btw from your question is not clear who maintains the connection property: mysql class or not?

answered Aug 08 '12 at 07:43

softius

166
5

all work with mysql is in the mysql class, which is extended. From authorization(missed one letter in first post) i just call methods with parameters which returns data from db. The problem is that i thought that when i extend class constructor automatically creates new object with connection in extended class, but as is see now i was wrong. – user1564141 Aug 08 '12 at 07:54

score 0 · Answer 2 · answered Aug 08 '12 at 07:26

0

for testing purposes try

function __destruct(){
    if ( !is_object($this->connection) ) {
        echo ' $this->connection is not an object', "\n";
        var_dump($this->connection);
        die;
    }
    if ( !method_exists($this->connection, 'close') ) {
        echo '$this->connection has no method close()', "\n";
        echo get_class($this->connection), "\n";
        die;
    }
    $this->connection->close();
}

answered Aug 08 '12 at 07:26

VolkerK

95,432
20
163
226

returns $this->connection is not an object NULL... But constructor creates new mysqli connections and i only want to close it. – user1564141 Aug 08 '12 at 07:30

fatal error when extending simple class

2 Answers2