Using $this when not in object context model class

Question

I have stated my bespoke MV, I have a simple Model + controller classes and I can't get the var in the model to be recognsed when called by a different function

The controller class is

  class StaffController {

    protected $module = "staff";

    public function __construct()
    {
        //include the staff Model
        require_once(MODEL_PATH.$this->module.'.php');
    }
    public function index() {

        // we store all the posts in a variable
        $staff = Staff::all();

        header('Content-Type: application/json');
        echo json_encode($staff);

    }

And $staff = Staff::all(); calls the model class, and its the $list variable that isn't recognized:

  class Staff {

    public $list = array();

    public function __construct() {
          $this->list = [];
    }


    public static function all() {
      //get all the staff 

      $temp = [];

      $db = Db::getInstance();

      $req = $db->query('SELECT * FROM data ORDER BY ParentID ASC');

      // we create a list of Post objects from the database results
      foreach($req->fetchAll() as $staff) { array_push($temp,$staff);

      self::reorderOrg($temp );

      return $final;
    }


    private static function reorderOrg($array, $parent = 0, $depth = 0){
          //reorganise org 

        for($i=0, $ni=count($array); $i < $ni; $i++){
            //check if parent ID same as ID

            if($array[$i]['parentID'] == $parent){

                array_push($this->list ,$array[$i]); //***** no being recognized

                self::reorderOrg($array, $array[$i]['id'], $depth+1);

            }
        }

        return true;
      }


  }

I get the following error Using $this when not in object context in and its to do with the array_push in the model class not liking $this->list. How do a set the private var so it can be used within its own class funcitons

You don't have a "this" context in a static method. You'd have to call `self::$list` instead of `$this->list`. — Maximilian Riegler, Apr 20 '16 at 06:46

score 2 · Accepted Answer · answered Apr 20 '16 at 06:45

The static keyword means that that function is called on the class itself, not on an instance of the class. That means $this doesn't refer to anything.

If it's a function that needs to be called on a specific instance so that you have access to its members, you'll need to either make it non-static or pass in an instance of the class (probably the former, since that's what a non-static method is for).

As far as having the class keep a list of its instances: What you're doing here is initializing a list on an instance of your class, so each instance will have an empty list. This may not be what you're intending.

score 0 · Answer 2 · answered Apr 20 '16 at 06:45

0

you are not in object context because your function is static. you have to use self instead. self refers to the current class:

array_push(self::list, $array[$i]);

answered Apr 20 '16 at 06:45

low_rents

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score 0 · Answer 3 · answered Apr 20 '16 at 06:47

You simple cannot use $this in static methods because static methods are not part of the instantiated object to which $this refers. Static methods can be called even if the object is not instantiated.

You have to make reorderOrg non-static in order to work.

score 0 · Answer 4 · answered Apr 20 '16 at 06:47

Please read about static methods and properties in PHP.

You can not access $this in static method because you do not have any instance of the class which should be referred as $this.

You have two options here

Declare property as static and access it with self keyword. For example

// Declaration

public static $list = array();

// Access

self::$list[] = 'something';
Create an object of the class and access property of the created object.

// Create object

$staff = new Staff();

// Access

$staff->list[] = 'something';

Remember to read the documentation!

score 0 · Answer 5 · edited May 23 '17 at 11:52

0

Related Post: Using this inside a static function fails

Does this answer your issue? When using a static method; you must use self:: not $this->

http://php.net/manual/en/language.oop5.static.php

array_push(self::list,...);

edited May 23 '17 at 11:52

Community

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1

answered Apr 20 '16 at 06:49

Louis Milotte

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Using $this when not in object context model class

5 Answers5