php return to page after form submission

Question

I've created a html form

<form action="http://localhost/php/insert.php" method="post">
    Barcode: <input type="text" name="barcode" /><br><br>
    Serial: <input type="text" name="serial" /><br><br>
    <input type="submit" />
</form>

which saves into my database using this php:

<?php
$con = mysql_connect("example","example","");
if ( ! $con) {
    die('Could not connect: ' . mysql_error());
}
mysql_select_db("database", $con);

$sql = "INSERT INTO asset (barcode, serial)
        VALUES ('$_POST[barcode]','$_POST[serial]')";

if ( ! mysql_query($sql, $con)) {
    die('Error: ' . mysql_error());
}
mysql_close($con)
?>

the form saves to the DB but the page just goes to http://localhost/php/insert.php when you press submit, which is a blank page. how can I make it stay on the same page and just show a message or something?

Answer 1

Note that redirecting with HTTP_REFERER is flaky and untrustworthy in general, so the best way is to have a URL sent with the request or, if it's coming from another server, you could build a specific pass-through to use for specific sites/URLs. The best is to know the URL by having it be submitted with the request; the other two are probably less than optimal.

After your form processing is done, do this before outputting anything (which will throw an error):

header("Location: {$_SERVER['HTTP_REFERER']}");
exit;

Depending on what your processing outcomes could be, you could append an error to the URL:

if ($query_does_not_execute) {
    $errcode = "error_code=003";
}

$referer = $_SERVER['HTTP_REFERER'];

if ($errcode) {
    if (strpos($referer, '?') === false) {
        $referer .= "?";
    }

    header("Location: $referer&$errcode");
} else {
    header("Location: $referer");
}
exit;

Then on the page, you could show the error. Or, alternatively, you could redirect to a page to handler errors of different kinds. This is wide-open to a number of different interpretations.

Answer 2

You can use PHP's Header() function like so:

header("Location: your-page.php");
exit;

You'll need to make sure there is no output (i.e. echoing anything, or any HTML etc) before the header call or it will not work.