Riad Riad - 6 months ago 66
PHP Question

PHP fat free framework using $this when not in object context?

I am developing a project using fat free PHP framework. In the documentation, they said you can build your own skeleton for the project, so my project directory is like the following:


  • assets


    • css

    • js


  • controllers


    • Controller.php

    • Home_Controller.php


  • lib (which has the framework stuff)

  • models


    • Model.php

    • Model_Home.php


  • views


    • home


      • main.html



  • index.php



in the index.php I am calling the framework (controllers and models including the database connection) and having my routes as the following:

// Kickstart the framework
$f3=require($_SERVER['DOCUMENT_ROOT'] . '/project_name/lib/base.php');
$f3->set('AUTOLOAD',''.$_SERVER['DOCUMENT_ROOT'] . '/project_name/controllers/; '.$_SERVER['DOCUMENT_ROOT'] . '/project_name/models/');

$f3->set('DEBUG',3);
if ((float)PCRE_VERSION<7.9){
trigger_error('PCRE version is out of date');
}

if (!($f3->get('DEBUG')))
{
$f3->set('ONERROR',
function($f3) {
$f3->reroute('/');
}
);
}

/****************** Start Routing the URLs ******************/

/****** Home Controller ******/
$f3->route('GET|HEAD /',
function($f3) {
$f3->reroute('/home');
}
);

$f3->route('GET|HEAD /index',
function($f3) {
$f3->reroute('/home');
}
);

$f3->route('GET /home','Controller_Home->main');

$f3->run();


inside Model.php I have a function that connect successfully to the database that I have like the following:

class Model
{
public $f3, $db;

public function connect()
{
global $db;

$username = 'username';
$password = 'password';
$hostname = 'hostname';
$dbname = 'dbname';

try{
$db = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
}
catch(PDOException $e){
echo $e->getMessage();
}
print_r($db); // this will give PDO Object ( )
$this->db = $db;
}
}
// if you try to execute query here, it will work.


Now, in Controller.php I am calling the connect() function in Model.php inside the construct like the following:

class Controller extends Model
{
public $f3, $db;

public function __construct($f3)
{
$this->f3 = $f3;
$this->connect();
}
}


Model_Home.php has functions that queries the database like the following:

class Model_Home extends Model
{
public $f3, $db;

public static function getUsers()
{
$query = "SELECT * FROM users";
$result = $this->db->query($query);
$output = '';
while ($row = $result->fetch(PDO::FETCH_ASSOC)) {
$output.= '<tr>
<td>'.$row['attrib1'].'</td>
<td>'.$row['attrib2'].'</td>
<td>'.$row['attrib3'].'</td>
<td>'.$row['attrib4'].'</td>
<td>'.$row['attrib5'].'</td>
</tr>';
}

return $output;
}
}


and Controller_Home.php will call the previous function statically and then call the right view to render the result like the following:

class Controller_Home extends Controller
{
public $f3, $db;

public function main($output = '')
{
//setting up the variables
$this->f3->set('getUsersTable', Model_Home::getUsers());
// getUsersTable is a variable that will be passed to the view to reder

//calling the view
$this->f3->set('main','views/home/main.html');
}
}


The last thing is the main.html page which is like the following:

<h1>All Users</h1></br>
<?php echo htmlspecialchars_decode($getUsersTable); ?>


when I run the code, it will give me an error message says:
Fatal error: Using $this when not in object context

project_name/models/Model_Home.php:8

which refers to the following line in Model_Home.php

$result = $this->db->query($query);


the php version that I have to use is 5.4 (pretty old). Any idea, please!

Thanks everyone!

sg- sg-
Answer

You have defined Model_Home::getUsers as a static method. This means it is a method of the class and not the instantiated object, which in turn means you don't get access to object properties, only class properties and methods defined as "static" . $db is not defined as "static" and therefore it's a property of the object and not the class.

If you want to keep getUsers as static:

You can either define $db as "static" (which will require other code changes for any code that references it), or use the Singleton pattern whereby an instance of an object is stored as a static class variable for access by other class methods. Eg:

class myClass
{
    protected static $db = null;

    public static function getDb()
    {
        if(empty(self::$db))
            self::$db = new Database();

        return self::$db;
    }
}

If you don't care about keeping getUsers static:

Just remove the "static" keyword from its declaration, and you will also have to update this method call from:

$this->f3->set('getUsersTable', Model_Home::getUsers());

to:

$modelHome = new Model_Home;
$this->f3->set('getUsersTable', $modelHome->getUsers());
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