Question

I have a GCM class which includes a send_notification function. In a different class, Demand.php, I am trying to use the send_notification function. So I have a constructor in Demand.php which points to my GCM class like this:

 $gcm = new GCM();

This $gcm variable is used in a function inside that class like this:

$result = $gcm->send_notification($registatoin_ids, $message);

That’s where I get the error:

<br />n<b>Fatal error</b>:  Call to a member function send_notification() on a non-object in..

I searched for the problem and found out that the problem is that $gcm is null and that’s why it’s calling nothing. So when I put the

$gcm = new GCM();

Inside my function it worked correctly. But is there no other way of doing this? I mean should it not be alright only by putting creating $gcm in the constructor of Demand.php?

Here are the parts where I am referring to:

function __construct() {
    require_once 'GCM.php';
    require_once 'DB_Connect.php';
    require_once 'DB_Functions.php';
    // connecting to database
    $this->db = new DB_Connect();
    $this->db->connect();
    $gcm = new GCM();
    $df = new DB_Functions();

}

// destructor
function __destruct() {

}


public function getDistance($uuid, $name, $distance, $latstart, $lonstart, $latend, $lonend, $gcm_regId) {
    $user_new = array ("$uuid", "$name", "$distance","$latstart", "$lonstart", "$latend", "$lonend","$gcm_regId");  
    $query = sprintf("SELECT uid, distance,latstart, lonstart, latend, lonend, gcm_regid, name FROM user_demand WHERE latstart='%s' AND lonstart='%s'",
    mysql_real_escape_string($latstart),
    mysql_real_escape_string($lonstart));
    $user = mysql_query($query);

    $no_of_rows = mysql_num_rows($user);

    while($user_old = mysql_fetch_assoc($user))
    {
        $djson = $this->findDistance($latend,$lonend,$user_old["latend"],$user_old["lonend"] );

        if ($user_old["distance"]+$distance>=$djson) {
            $match = mysql_query("INSERT INTO matched_users(gcm_a, gcm_b, name_a, name_b) VALUES(".$user_old['gcm_regid'].",".$user_new['gcm_regId'].",".$user_old['name'].",".$user_new['name'].")");
            $registatoin_ids = array($gcm_regId);
            $message = array("var" => $name);
            $result = $gcm->send_notification($registatoin_ids, $message);
        }
    }
}

Answer 1

If you put $gcm = new GCM(); in the constructor of your Demand class, then the variable $gcm will only be available in the constructor method.

If you want to be able to access the $gcm variable throughout the Demand class you’ll need to set it as a property of the class like so:

class Demand()
{
    /**
     * Declare the variable as a property of the class here
     */
    public $gcm;

    ...
    function __construct()
    {
        ...
        $this->gcm = new GCM();
        ...
    }

    function myFunction()
    {
        ...
        // You can access the GCM class now in any other method in Demand class like so:
        $result = $this->gcm->send_notification($registatoin_ids, $message);
        ...
    }
    ...
}