Form waits for second submission to push through first submission - php

Question

I'm new to development and I'm trying to build a contact form using php that pulls the info from a contact form. My contact form works and collects the data as needed, but when I click submit the first time I don't receive the information to my inbox. When I refresh the page, complete the form a second time and click submit once more, I receive both submissions to my inbox at the same time. It's as if the first submission waits to be pushed through by the second submission. Can anyone explain why this is happening and how to stop it?
I've seen a lot of posts regarding submissions happening twice but my issue is the first doesn't come through until the second is sent.
Here is my PHP
if (isset($_POST['submit'])) {
$name = $_POST['name'];
$subject = $_POST['subject'];
$mailFrom = $_POST['email'];
$phone = $_POST['phone'];
$address = $_POST['address'];
$body = $_POST['body'];
$radio = $_POST['time'];
$mailTo = "myemail#gmail.com";
$headers = "From: " . $mailFrom;
$txt = "You have received an enquiry from: " . $name .
"\n\n Phone Number: " . $phone .
"\n\n Address: " . $address .
"\n\n Message: " . $body .
"\n\n Time to call: " . $radio;
mail($mailTo, $subject, $txt, $headers);
header("Location: index-contact.php?submission");
}
I'm testing on localhost8888 using MAMP Pro.
Here is HTML:
<form class="contact-form" action="contactform.php" method="post" id="form">
<label for="name">Full Name:</label><br>
<input type="text" id="name" name="name" placeholder="Please enter your name" required>
<label for="email">Email Address:</label><br>
<input type="email" id="email" name="email" placeholder="Please enter your email address" required>
<label for="phone">Phone Number:</label><br>
<input type="text" id="phone" name="phone" placeholder="Please enter your phone number" required></input>
<label for="subject">Subject</label><br>
<input type="text" id="subject" name="subject" placeholder="Please enter a subject" required></input>
<label for="address">Postcode:</label><br>
<input type="text" name="address" placeholder="Please enter your postcode"></input><br>
<label for="body">Comments:</label><br>
<textarea name="body" placeholder="Please enter your message"></textarea>
<input type="radio" id="morning" name="time" value="morning">Morning</input>
<input type="radio" id="afternoon" name="time" value="afternoon">Afternoon</input>
<input type="radio" id="anytime" name="time" value="anytime">Anytime</input>
<button type="submit" id="submit" name="submit">Send Message</button>
</form>

Answer 1

This happens because when you update the page, you will be resending the POST.
As this is a contact form, i suggest installing Google reCaptcha. Thus, it will be necessary to resolve the captcha and this will not happen.
There are other ways. One of them would be to store user data in a database and only authorize a sending by IP or session at a certain time.
Or you can just work with direct session and prevent this from happening, using the function in your code:
function prevent_multi_submit($type = "post", $excl = "contact") {
$string = "";
foreach ($_POST as $key => $val) {
// this test is to exclude a single variable, f.e. a captcha value
if ($key != $excl) {
$string .= $val;
}
}
if (isset($_SESSION['last'])) {
if ($_SESSION['last'] === md5($string)) {
return false;
} else {
$_SESSION['last'] = md5($string);
return true;
}
} else {
$_SESSION['last'] = md5($string);
return true;
}
}
Your code will look like this:
session_start();
if (isset($_POST['submit']) and prevent_multi_submit()) {
$name = $_POST['name'];
$subject = $_POST['subject'];
$mailFrom = $_POST['email'];
$phone = $_POST['phone'];
$address = $_POST['address'];
$body = $_POST['body'];
$radio = $_POST['time'];
$mailTo = "myemail#gmail.com";
$headers = "From: " . $mailFrom;
$txt = "You have received an enquiry from: " . $name .
"\n\n Phone Number: " . $phone .
"\n\n Address: " . $address .
"\n\n Message: " . $body .
"\n\n Time to call: " . $radio;
mail($mailTo, $subject, $txt, $headers);
header("Location: index-contact.php?submission");
}
EDIT 1:
Or, add a simple parameter to the URL that redirects, so that a second POST is not authorized:
if (isset($_POST['submit']) and $_GET["sent"] != "ok") {
$name = $_POST['name'];
$subject = $_POST['subject'];
$mailFrom = $_POST['email'];
$phone = $_POST['phone'];
$address = $_POST['address'];
$body = $_POST['body'];
$radio = $_POST['time'];
$mailTo = "myemail#gmail.com";
$headers = "From: " . $mailFrom;
$txt = "You have received an enquiry from: " . $name .
"\n\n Phone Number: " . $phone .
"\n\n Address: " . $address .
"\n\n Message: " . $body .
"\n\n Time to call: " . $radio;
mail($mailTo, $subject, $txt, $headers);
header("Location: index-contact.php?sent=ok");
}
Read more about HTTP GET variables at PHP.net