Showing message after redirect

Question

I'm trying to show a message after a successful redirect in my project, but can't find a really good way to do so. Right now I have a very simple and not really good solution which looks like this:

// Things happened:
$Alert = dangerMessage("Heyho, I am a message!");
header('refresh: 1.5 ; url = index.php');

My dangerMessage is a simple echo of a predefined Alertbox:

function dangerMessage($text) {
    return "<div class='alert alert-danger alert-dismissable fade show mt-4'>
    <a href='#' class='close' data-dismiss='alert' aria-label='close'>&times;</a>".$text."</div>";
}

It simply shows a little box with text inside.

Anyway, like I said this is my "simple" solution right now, it works fine but it's not the best solution. I know that you should be putting a die(); or a exit(); after the header(), but my problem is that when I put them under my header() the page is just blank for 1.5 seconds, redirects, and shows no messagebox.

Is there a way to have a decent/good redirect that also shows my message?

Answer 1

An elegant and common approach is to use a flash message. This is basically a one-off session entry which is set in one request and is delivered in the next one, then instantly deleted. Consider the following example.

On the redirecting page, you set the flash message in the session object:

$_SESSION["flash"] = ["type" => "success", "message" => "You are great!"];

On a target page, check if there’s a flash message. If so, output and delete it.

if (isset($_SESSION["flash"]))
{
    vprintf("<p class='flash %s'>%s</p>", $_SESSION["flash"]);
    unset($_SESSION["flash"]);
}

Note: The example assumes you are using PHP sessions already. If not, you must start the session first.

Answer 2

I would advise you use a session to display your message. The issue with $_GET is that since you rely on the URL, anyone can constantly manipulate the message being displayed.

Before calling header(), save the success or failed message to a session variable. For example

$_SESSION['success'] = 'Data Saved to Database';

On the index page, check for the session key, echo it and then remove it from the session array.

if(!empty($_SESSION['success'])){
  echo $_SESSION['success'];
 unset($_SESSION['success']);//so you do not have to display it over and over again
}