php header not working after applying jQuery - php

Question

// script.js
$(document).ready(function(){
$(".loginProzor").hide();
$(".login").click(function(){
$(".loginProzor").fadeToggle(300);
});
$("#prijavi").click(function(){
if($("#user").val() == "" || $("#pass").val() == ""){
$("#labelGreska").html("Unesite korisničke podatke");
}
else{
$.post($("#forma").attr("action"), $("#forma :input").serialize(),
function(data){
$("#labelGreska").html(data);
});}
$("#forma").submit(function(){
return false;
});
});
});
// form
<form id="forma" action="login.php" method="post">
<label>Korisničko ime</label><br>
<input type="text" name="user" id="user"><br>
<label>Lozinka</label><br>
<input type="password" name="pass" id="pass"><br>
<input type="submit" value="Prijavi se" id="prijavi">
<label id="labelGreska"></label>
</form>
//login.php
<?php
include 'funkcije.php';
include 'spojiBazu.php';
$user = $_POST['user'];
$pass = $_POST['pass'];
if(!$user){
$greske[] = 'Unesite korisničko ime';
}
$pass = md5($pass);
$ucitaj = mysql_query("select * from login where username = '$user' and password = '$pass'");
session_start();
if(mysql_num_rows($ucitaj) === 0){
echo 'Korisnički podaci nisu validni, molimo pokušajte ponovo.';
}else{
$korisnik = mysql_query("select username from login where username = '$user'");
$podatak = mysql_result($korisnik, 0);
$_SESSION['user'] = $podatak;
header("Location: index.php");
}
?>
Hello
I'm learning web development and I ran into a problem. I created simple login form. It evaluates some errors using jQuery and the rest of errors are evaluated using PHP. Everything works except Header command in PHP. When user succesfully logs in, header command should redirect to index.php so user can verify it is logged in, but in this case header tag don't work.
Before applying jQuery (all errors were handled by PHP) header command worked with no problems. Can you tell what's wrong here?

Answer 1

Details,
Since AJAX happens "behind the scenes" (so to speak) your redirect will just interrupt the response to your javascript handler. So PHP cannot redirect your browser now, jQuery can. So use jQuery to redirect the user.
You'll need to return the URL and have your callback kick the browser to a new location.
On this note, since you have to return data to the front end, you'll want to add a status or similar variable so that you can switch your front end behavior based on whether the call "failed" or not.
Exactly what Marc B pointed,
"You're doing the ajax call - the php header will redirect the ajax response... not the page that the user is currently sitting on. You will have to modify your javascript code in the client to change the location."
A javascript redirect is as simple as window.location.href = "http://mylocation";.
Solution to your problem,
JQUERY
// script.js
$(document).ready(function(){
$(".loginProzor").hide();
$(".login").click(function(){
$(".loginProzor").fadeToggle(300);
});
$("#prijavi").click(function(){
if($("#user").val() == "" || $("#pass").val() == ""){
$("#labelGreska").html("Unesite korisničke podatke");
}
else{
$.post($("#forma").attr("action"), $("#forma :input").serialize(),
function(data){
if(data=="success"){
window.location.href = "index.php";
} else{
alert("login failed");
}
});
}
$("#forma").submit(function(){
return false;
});
});
});
PHP
<?php
include 'funkcije.php';
include 'spojiBazu.php';
$user = $_POST['user'];
$pass = $_POST['pass'];
if(!$user){
$greske[] = 'Unesite korisničko ime';
}
$pass = md5($pass);
$ucitaj = mysql_query("select * from login where username = '$user' and password = '$pass'");
session_start();
if(mysql_num_rows($ucitaj) === 0){
echo 'failed';
exit;
}else{
$korisnik = mysql_query("select username from login where username = '$user'");
$podatak = mysql_result($korisnik, 0);
$_SESSION['user'] = $podatak;
echo "success";
}
?>

Answer 2

from http://www.php.net/manual/en/function.header.php
Remember that header() must be called before any actual output is
sent, either by normal HTML tags, blank lines in a file, or from PHP.
It is a very common error to read code with include, or require,
functions, or another file access function, and have spaces or empty
lines that are output before header() is called.
You can try with a javascript redirection or remake your source code with the header at the begining

Answer 3

header() will not work after output has been echoed to the screen.
Check funkcije.php and spojiBazu.php to see if any echo happening. If they are you need to find a way to remove the echos from those to included files before you call header() in login.php.