initialise instances inside a class php - php

Question

How do I initialize objects inside a function within a class? so I can call each object like page[0]->getTitle(); or page[1]->getDescription();
The error now says :
Fatal error: Using $this when not in object context in C:\xampp\htdocs\class.page.php on line 92
index.php
Page::createObjects();
and my page.class.php
private title;
private description;
private page;
public function __construct($title="", $description=""){
$this->title = $title;
$this->description = $description;
}
public static function createObjects(){
$database = new database();
$database->query('SELECT * FROM pages');
for($i=0;$i<$totalRows;$i++){
//line 92 here
$this->page[$i] = new self("Title", "Description");
}
}

Answer 1

You might consider having two different classes here, Page (page.class.php) and Pages (pages.class.php). Your Page class will represent an individual page record from your database, and your Pages class will contain methods that work on a set of records.
page.class.php
<?php
class Page
private title;
private description;
public function __construct($title="", $description=""){
$this->title = $title;
$this->description = $description;
}
public function getTitle()
{
return $this->title;
}
public function getDescription()
{
return $this->description();
}
}
?>
pages.class.php
<?php
class Pages
public static function createObjects(){
$pages = array();
$database = new database();
$database->query('SELECT * FROM pages');
for($i=0;$i<$totalRows;$i++){
//line 92 here
$pages[] = new Page("Title", "Description");
}
return $pages;
}
}
?>
Then in your index.php, you get your Page objects from Pages
index.php
<?php
$pages = Pages::createObjects();
// to get the title of the first object
echo $pages[0]->getTitle();
?>

Answer 2

Like others commented, you can't access $this from a static function
a static field/variable/property/method belong to the class, not to a specific instance
<?php
class VIP
{
private $name, $surname;
private static $vips = array();
function __construct($name, $surname){
$this->name = $name;
$this->surname = $surname;
self::$vips[] = $this;
}
function getCredentials(){
return $this->name . ", " . $this->surname;
}
static function getAll(){
return self::$vips;
}
}
$a = new VIP("George", "Clooney");
$b = new VIP("Scarlet", "Johansson");
$c = new VIP("Brad", "Pitt");
$d = new VIP("Emma", "Stone");
echo $a->getCredentials() . "\n";
foreach(VIP::getAll() as $vip)
echo $vip->getCredentials() . "\n";
?>
demo: https://eval.in/161874
however, this is more than likely bad code, since you are a beginner you should forget of static fields and methods and just use regular ones
better code:
<?php
class VIP
{
private $name, $surname;
function __construct($name, $surname){
$this->name = $name;
$this->surname = $surname;
}
function getCredentials(){
return $this->name . ", " . $this->surname;
}
}
class VIPsList
{
private $storage = [];
function add(VIP $vip){
$this->storage[] = $vip;
}
function getAll(){
return $this->storage;
}
}
$a = new VIP("George", "Clooney");
$b = new VIP("Scarlet", "Johansson");
$c = new VIP("Brad", "Pitt");
$d = new VIP("Emma", "Stone");
$collection = new VIPsList();
$collection->add($a);
$collection->add($b);
$collection->add($c);
$collection->add($d);
echo $a->getCredentials() . "\n";
foreach($collection->getAll() as $vip)
echo $vip->getCredentials() . "\n";
?>
https://eval.in/161898