Reload a function without reloading the page - php

Question

I want to callout a function without the page is reloading.
I know that this is possible with AJAX but i don't know how it works with calling a function.
I want to put a timer so it will reload the function every 3 seconds, so the users doesnt need to reload the page everytime to see if there is a new message.
$object = new Messages();
$object->ShowMessage($nick);
ShowMessage(); is the function that i want to call out every 3 seconds.
Full code :
public function ShowMessage() {
$st = $this->db->prepare("SELECT * FROM bericht");
$st->execute();
if($st->rowCount() == 0){
echo 'There is no message jet!';
}
foreach ($st as $bericht){
$uid = $bericht['uid'];
$nick = $this->db->prepare("SELECT * FROM users WHERE id=?");
$nick->bindParam(1, $uid);
$nick->execute();
foreach($nick as $name) {
$image = $name['foto'];
if($image == 'nophoto.jpg'){
echo '<img src="image/nophoto.jpg" width="60px" height="30px">';
} else {
echo '<img src="image/'; echo $image.'"'; echo ' width="60px" height="30px">';
}
echo json_encode($name['name']) .': ';
echo json_encode($bericht['message']).' <br> ';
}
}
}

Answer 1

You can do that with ajax. In order to do that, you need to implement ajax client function on frontend and a handler for processing ajax request. In frontend you can use jquery for ajax operations;
setInterval(function() {
$.get( "handler.php", function( data ) {
// You can use data. It is in json format.
// Ex: alert(data.message) . "message" is one of the
// fields of returned array in php handler file
});
}, 3000);
handler.php
<?php
$object = new Messages();
$result = $object->ShowMessage($nick);
// I assume this returns array.
// Ex: array("type" => "error", "message" => "Error occured on feed");
echo json_encode($result);
?>
Update: If you do not want to use json data
Update your code like below. Only use echo, you do not need to return json data.
public function ShowMessage() {
$st = $this->db->prepare("SELECT * FROM bericht");
$st->execute();
if($st->rowCount() == 0){
echo 'There is no message jet!';
}
foreach ($st as $bericht){
$uid = $bericht['uid'];
$nick = $this->db->prepare("SELECT * FROM users WHERE id=?");
$nick->bindParam(1, $uid);
$nick->execute();
foreach($nick as $name) {
$image = $name['foto'];
if($image == 'nophoto.jpg'){
echo '<img src="image/nophoto.jpg" width="60px" height="30px">';
} else {
echo '<img src="image/'; echo $image.'"'; echo ' width="60px" height="30px">';
}
echo $name['name'] .': ';
echo $bericht['message'].' <br> ';
}
}
}
and in js;
setInterval(function() {
$.get( "handler.php", function( data ) {
// alert(data);
});
}, 3000);

Answer 2

You need to do that integrating javascript to your php code.
Using jquery, you can take a look at $.post function. You can rise the event with the javascript function window.setInterval(yourFunction(),3000)
You also need to create a php page that will reply to the Ajax request, that will be passed as a parameter to the $.post

Answer 3

Just call that script via ajax:
.html:
setInterval(function(){
$.ajax({
url: "showMessageScript.php",
type: "post",
data: {nick: $("#nick").val(), token: <?php echo $_SESSION['token']; ?>},
success: function(jsonData){
$('#display').text(jsonData['message']);
}
});
},
3000);
showMessageScript.php:
function showMessage($nick) {
$object = new Messages();
$object->ShowMessage($nick);
echo json_encode(array('message': 'Your message is here'));
}
// check if authorized to do some action
if (!empty($_SESSION['token']) && $_SESSION['token'] == $_POST['token'] && !empty($_POST['nick'])) {
showMessage($nick);
} else {
echo json_encode(array('message': 'not authorized'));
}