Notice: Trying to get property 'X' of non-object

Question

I am getting this error (Notice: Trying to get property 'X' of non-object) while trying to access to the members of one object that I know that exist ($newStudent = new student();) . Does anybody knows what can be the issue?

It fails while running this part:

if (isset($_POST['submit'])) {
    $newStudent = new student();

    if(is_object($newStudent)){
        $newStudent->settForNavn(htmlentities($_POST['fornavn']));
        $newStudent->settEtterNavn(htmlentities($_POST['etternavn']));
        $newStudent->settEpost(htmlentities($_POST['epost']));
        $newStudent->settMobil(htmlentities($_POST['mobil']));
        $id = $studReg->leggTilStudent($newStudent);
        print ("<a href=" . $_SERVER['PHP_SELF'] . ">Tilbake</a>");}
}

Errors:

Notice: Trying to get property 'Fornavn' of non-object in C:\xampp\htdocs\lab3\oppgave\student.class.php on line 42

Notice: Trying to get property 'Etternavn' of non-object in C:\xampp\htdocs\lab3\oppgave\student.class.php on line 45

Notice: Trying to get property 'ola@gmail.com' of non-object in C:\xampp\htdocs\lab3\oppgave\student.class.php on line 55

Notice: Trying to get property 'Mobilnummer' of non-object in C:\xampp\htdocs\lab3\oppgave\student.class.php on line 48

StudentRegister.php

<?php

spl_autoload_register(function ($class_name) {
    require_once $class_name . '.class.php';
});
require_once 'auth.php';

$studReg = new StudentRegister($db);

if (isset($_POST['submit'])) {
    $newStudent = new student();

    if(is_object($newStudent)){
        $newStudent->settForNavn(htmlentities($_POST['fornavn']));
        $newStudent->settEtterNavn(htmlentities($_POST['etternavn']));
        $newStudent->settEpost(htmlentities($_POST['epost']));
        $newStudent->settMobil(htmlentities($_POST['mobil']));
        $id = $studReg->leggTilStudent($newStudent);
        print ("<a href=" . $_SERVER['PHP_SELF'] . ">Tilbake</a>");}
}


else if(isset($_GET['id']) && ctype_digit($_GET['id']))
{
    $id = intval($_GET['id']);
    if($student = $studReg->visStudent($id)) {

        print("Navn: "   . $student->hentNavn() . "<br />\n");
        print("Klasse:      ". $student->hentKlasse() . "<br />\n");
        print("Mobil: "   . $student->hentMobil() . "<br />\n");
        print("Epost:      ". $student->hentEpost() . "<br />\n");
        print ("<a href=" . $_SERVER['PHP_SELF'] . ">Tilbake</a>");
    }
    else {
        // Ingen poster
        echo "Beklager, fant ingen poster!";
    }
}


else {
    print("Studenter:<br>");

    $studenter = $studReg->visAlle();
    foreach ($studenter as $student )
    {
        print("<a href=" . $_SERVER['PHP_SELF'] . "?id=" . $student->hentId() . ">". $student->hentNavn() .  "</a><br/>\n");
    }

    print("<br>");
    print("<br>");
    print("Add a new student to the DB:<br>");

    print('
        <div class= "black">
           <form method="post">
           <input type="hidden"  name="id" value=""><br>
           <div> 
                <label for="Fornavn: "</label>
                <input type="text" name="fornavn" value="Fornavn" required><br>
           </div> 
           <br>
           <div> 
                <label for="Etternavn: "</label>
                <input type="text" name="etternavn" value="Etternavn" required><br>
           </div> 
           <br>
           <div> 
                <label for="E-post "</label>
                <input type="email" name="epost" value="E-post" required><br>
           </div> 
           <br>
           <div>

                <label for="Mobilnummer "</label>
                <input type="text" name="mobil" value="Mobilnummer" required><br>
           </div> 
           <br> 
           <br> 
           <button type="submit" name="submit">Submit</button>
           </form>
           </div> 
        ');

}

?>

student.class.php

<?php
class student {
    private $id;
    private $etternavn;
    private $fornavn;
    private $klasse;
    private $mobil;
    private $www;
    private $epost;

    function __construct() {
    }

    //Getters
    function hentId() {
        return $this->id;
    }
    function hentNavn() {
        return $this->fornavn . " " . $this->etternavn;
    }
    function hentForNavn() {
        return $this->fornavn;
    }
    function hentEtterNavn() {
        return $this->etternavn;
    }
    function hentMobil() {
        return $this->mobil;
    }
    function hentKlasse() {
        return $this->klasse;
    }
    function hentEpost() {
        return $this->epost;
    }
    function hentURL() {
        return $this->www;
    }
    //Setters
    function settForNavn($fornavn) {
        $this->fornavn->$fornavn;
    }
    function settEtterNavn($etterNavn) {
        $this->etternavn->$etterNavn;
    }
    function settMobil($mobil) {
        $this->mobil->$mobil;
    }

    function settKlasse($klasse) {
        $this->klasse->$klasse;
    }
    function settEpost($epost) {
        $this->epost->$epost;
    }
}

Answer 1

In your student class, the setters should be set like the following

//Setters
function settForNavn($fornavn) {
    $this->fornavn = $fornavn;
}
function settEtterNavn($etterNavn) {
    $this->etternavn = $etterNavn;
}
function settMobil($mobil) {
    $this->mobil = $mobil;
}

function settKlasse($klasse) {
    $this->klasse = $klasse;
}
function settEpost($epost) {
    $this->epost = $epost;
}